Hans-Christoph Becker, MD

Abstract

To demonstrate non-inferiority of iobitridol 350 for coronary CT angiography (CTA) compared to higher iodine content contrast media regarding rate of patients evaluable for the presence of coronary artery stenoses.In this multicentre trial, 452 patients were randomized to receive iobitridol 350, iopromide 370 or iomeprol 400 and underwent coronary CTA using CT systems with 64-detector rows or more. Two core lab readers assessed 18 coronary segments per patient regarding image quality (score 0 = non diagnostic to 4 = excellent quality), vascular attenuation, signal and contrast to noise ratio (SNR, CNR). Patients were considered evaluable if no segment had a score of 0.Per-patient, the rate of fully evaluable CT scans was 92.1, 95.4 and 94.6% for iobitridol, iopromide and iomeprol, respectively. Non-inferiority of iobitridol over the best comparator was demonstrated with a 95% CI of the difference of [-8.8 to 2.1], with a pre-specified non-inferiority margin of -10%. Although average attenuation increased with higher iodine concentrations, average SNR and CNR did not differ between groups.With current CT technology, iobitridol 350mg iodine/ml is not inferior to contrast media with higher iodine concentrations in terms of image quality for coronary stenosis assessment. Iodine concentration is an important parameter for image quality in coronary CTA. Contrast enhancement must be balanced against the amount of iodine injected. Iobitridol 350 is non-inferior compared to CM with higher iodine concentrations. Higher attenuation with higher iodine concentrations, but no SNR or CNR differences.

View details for DOI 10.1007/s00330-016-4437-9

View details for PubMedID 27271922

Abstract

Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions. To characterize stochastic radiation risks of patients from these studies, life-time attributable cancer risks (LAR) were estimated using sex-, age-, and organ-specific risk models based on the hypothesis of a linear non-threshold dose-response relationship. For the brain, heart and pelvic cancer studies considered, local absorbed doses in the imaging field were about 100-190 mGy (total CTDI(vol), 200 mGy), 15-30 mGy (16 mGy) and 80-270 mGy (140 mGy), respectively. According to a recent publication of the International Commission on Radiological Protection (ICRP Publication 118, 2012), harmful tissue reactions of the cerebro- and cardiovascular systems as well as of the lenses of the eye become increasingly important at radiation doses of more than 0.5 Gy. The LARs estimated for the investigated cerebral and myocardial DCE-CT scenarios are less than 0.07% for males and 0.1% for females at an age of exposure of 40 years. For the considered tumor location and protocol, the corresponding LARs are more than 6 times as high. Stochastic radiation risks decrease substantially with age and are markedly higher for females than for males. To balance the diagnostic needs and patient protection, DCE-CT studies have to be strictly justified and carefully optimized in due consideration of the various aspects discussed in some detail in this review.

View details for DOI 10.1016/j.ejrad.2014.11.011

View details for Web of Science ID 000367357700002

View details for PubMedID 25480677

Abstract

We aimed to compare safety and efficacy of the direct thrombin inhibitor bivalirudin with unfractionated heparin (UFH) during transcatheter aortic valve implantation (TAVI).In this retrospective analysis, 461 patients underwent TAVI between 2007 and 2012; 339 patients received bivalirudin, and 122 patients received UFH. In the bivalirudin group, the Sapien XT valve was implanted in 159 (46.9%) patients, and 180 (53.1%) received a Medtronic CoreValve. In the UFH group, only the Medtronic CoreValve was implanted. The primary outcome of interest was the incidence of any bleeding. Secondary outcomes of interest were all-cause mortality and cardiovascular mortality at 72 hours after the procedure and at 30 days.No significant difference between the groups was observed for life-threatening bleeding (2.4% for bivalirudin vs 3.3% for UFH; P = 0.59), major bleeding (8.3% vs 8.2%, respectively; P = 0.98) and minor bleeding (8.3% vs 7.4%, respectively; P = 0.76). At 72 hours after the procedure, all-cause mortality was 3.0% in the bivalirudin group and 3.3% for the UFH group (P = 0.88), whereas cardiovascular mortality was 3.0% in the bivalirudin group and 2.5% in the heparin group (P = 0.77). At 30 days, all-cause mortality was 5.3% vs 4.1% in the bivalirudin and heparin groups (P = 0.57) and cardiovascular mortality was 4.4% vs 2.5% (P = 0.33). Device success (Valve Academic Research Consortium 2 composite end point) was 94.0% in the bivalirudin-treated and 92.6% in the UFH-treated patients (P = 0.60). The early safety at 30 days was 85.3% in the bivalirudin-treated group compared with 83.6% in the UFH-treated group (P = 0.65).Bivalirudin has a safety and efficacy profile similar to weight-adjusted UFH during the TAVI procedure.

View details for DOI 10.1016/j.cjca.2015.02.029

View details for Web of Science ID 000358425800009

View details for PubMedID 26211708

Abstract

To identify independent predictors of contrast medium-induced acute kidney injury (CI-AKI) after enhanced multidetector-row computed tomography (MDCT) prior to transcatheter aortic valve implantation (TAVI) in high-risk patients.The present single-centre study analysed retrospectively 361 patients who were assessed using MDCT prior to TAVI. CI-AKI was defined as an increase in serum creatinine (SCr) of 25% or 0.5 mg/dl in at least one sample over baseline (24 h before MDCT) and at 24, 48, and 72 h after MDCT.A total of 38 patients (10.5%) experienced CI-AKI. As compared to patients without CI-AKI, they presented more frequently with estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2), (81.6% versus 64.4%, p = 0.045) and tended to receive higher volumes of iodinated contrast media (ICM; 55.3% versus 39%, p = 0.057). There was a significant interaction between baseline eGFR and the amount of intravenous ICM administered (pfor interaction = <0.001) identifying the amount of ICM >90 ml as independent predictive factor of CI-AKI only in patients with baseline eGFR <60 ml/min/1.73m(2) (OR 2.615; 95% CI: 1.21-5.64).One in ten elderly patients with aortic stenosis undergoing MDCT to plan a TAVI procedure experienced CI-AKI after intravenous ICM injection. Intravenous administration of <90 ml of ICM reduces this risk in patients with or without pre-existing impaired renal function. However, in the majority of patients renal function recovers before the TAVI procedure.

View details for DOI 10.1016/j.crad.2014.05.106

View details for Web of Science ID 000342881800007

View details for PubMedID 25017451

Abstract

To evaluate the predictive value of CT-derived measurements of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI) and to calculate optimal cutoff values for the selection of various prosthesis sizes.The local IRB waived approval for this single-center retrospective analysis. Of 441 consecutive TAVI-patients, 90 were excluded (death within 30 days: 13; more than mild aortic regurgitation: 10; other reasons: 67). In the remaining 351 patients, the CoreValve (Medtronic) and the Edwards Sapien XT valve (Edwards Lifesciences) were implanted in 235 and 116 patients. Optimal prosthesis size was determined during TAVI by inflation of a balloon catheter at the aortic annulus. All patients had undergone CT-angiography of the heart or body trunk prior to TAVI. Using these datasets, the diameter of the long and short axis as well as the circumference and the area of the aortic annulus were measured. Multi-Class Receiver-Operator-Curve analyses were used to determine the predictive value of all variables and to define optimal cutoff-values.Differences between patients who underwent implantation of the small, medium or large prosthesis were significant for all except the large vs. medium CoreValve (all p's<0.05). Furthermore, mean diameter, annulus area and circumference had equally high predictive value for prosthesis size for both manufacturers (multi-class AUC's: 0.80, 0.88, 0.91, 0.88, 0.88, 0.89). Using the calculated optimal cutoff-values, prosthesis size is predicted correctly in 85% of cases.CT-based aortic root measurements permit excellent prediction of the prosthesis size considered optimal during TAVI.

View details for DOI 10.1371/journal.pone.0103481

View details for Web of Science ID 000339819800047

View details for PubMedID 25084451

Abstract

Previous clinical studies have shown that iso-osmolar iodixanol (Visipaque) causes less patient discomfort than low-osmolar contrast media (LOCM) when administered via intra-arterial injection. No data are available comparing these agents for patient discomfort when administered intravenously (i.v.) using power injectors.To compare the frequency and intensity of patient discomfort between iodixanol and iopamidol (Isovue) administered i.v. using a power injector in contrast-enhanced computed tomography (CECT) of the abdomen and pelvis.This was a prospective, randomized, double-blind, multicenter study of iodixanol 320mg I/mL or iopamidol 370mg I/mL on patient discomfort. The presence of discomfort (heat, pain, coldness) and intensity was verbally rated by patients on a 0-10 scale and converted into four categories (0, none; 1-3, mild; 4-7, moderate; 8-10, severe). Image quality was evaluated.Of the 299 evaluable patients enrolled at nine centers, 151 received iodixanol and 148 received iopamidol. The average age was 58 years. Iodixanol patients experienced significantly less moderate/severe discomfort (35.1% vs. 67.3%; P<0.0001) or heat (29.8% vs. 63.9%; P<0.0001), and severe discomfort (2.6% vs. 16.3%; P=0.0004) or heat (2.6% vs. 15%; P=0.0008), but three times more no discomfort (21.2% vs. 7.5%; P=0.0008) than iopamidol patients. Excellent image quality was in 95.4% of iodixanol vs. 89.9% of iopamidol patients (P=0.0508). Overall, adverse event (AE) rate excluding patient discomfort was 19.9% in the iodixanol group and 14.9% in the iopamidol group (P=0.2870), but contrast-related AEs were comparable: 11.3% vs. 10.1% (P=0.8522). Delayed skin reactions occurred in 2.6% of patients in the iodixanol group and in no patient in the iopamidol group (P=0.1226).Patients receiving iodixanol had significantly lower moderate-to-severe or severe discomfort than patients receiving iopamidol, with heat being the major contributor. Iodixanol use trended towards better image quality but the difference was not statistically significant. No significant differences in incidences of overall or contrast-related AEs or delayed skin reactions were seen between the two groups. These data support that CM osmolality may be a key determinant of patient discomfort.

View details for DOI 10.1177/0284185113505277

View details for Web of Science ID 000338447900011

View details for PubMedID 24060817

Abstract

The diagnostic performance of multidetector row CT to detect coronary artery stenosis has been evaluated in numerous single-center studies, with only limited data from large cohorts with low-to-intermediate likelihood of coronary disease and in multicenter trials. The Multicenter Evaluation of Coronary Dual-Source CT Angiography in Patients with Intermediate Risk of Coronary Artery Stenoses (MEDIC) trial determines the accuracy of dual-source CT (DSCT) to identify persons with at least 1 coronary artery stenosis among patients with low-to-intermediate pretest likelihood of disease.The MEDIC trial was designed as a prospective, multicenter, international trial to evaluate the diagnostic performance of DSCT for the detection of coronary artery stenosis compared with invasive coronary angiography. The study includes 8 sites in Germany, India, Mexico, the United States, and Denmark. The study population comprises patients referred for a diagnostic coronary angiogram because of suspected coronary artery disease with an intermediate pretest likelihood as determined by sex, age, and symptoms. All evaluations are performed by blinded core laboratory readers.The primary outcome of the MEDIC trial is the accuracy of DSCT to identify the presence of coronary artery stenoses with a luminal diameter narrowing of 50% or more on a per-vessel basis. Secondary outcome parameters include per-patient and per-segment diagnostic accuracy for 50% stenoses and accuracy to identify stenoses of 70% or more. Furthermore, secondary outcome parameters include the influence of heart rate, Agatston score, body weight, body mass index, image quality, and diagnostic confidence on the accuracy to detect coronary artery stenoses >50% on a per-vessel basis.The results of the MEDIC trial will assess the clinical utility of coronary CT angiography in the evaluation of patients with intermediate pretest likelihood of coronary artery disease.

View details for DOI 10.1016/j.jcct.2014.04.006

View details for PubMedID 24939066

Abstract

To assess the feasibility of transcatheter aortic valve implantation (TAVI; Medtronic CoreValve and Edwards SAPIEN XT) under local anaesthesia with only mild analgesic medication and fluoroscopic guidance.461 patients underwent TAVI under local anaesthesia with lidocaine. The procedure was performed successfully in 459 of the cases. All patients were also treated with piritramide, metoclopramide hydrochloride and 62 mg dimenhydrinate. Monitoring consisted of a six-electrode, virtual 12-lead ECG, pulse oximetry, and invasive arterial pressure measurement. There was no continuous surveillance by an anaesthesiologist.There was no need for conversion to general anaesthesia except in four patients who required cardiopulmonary resuscitation. Conscious sedation with intravenous administration of midazolam for agitation or inotropic medication for prolonged hypotension was necessary in only seven of the 461 patients. The combined safety end point according to the Valve Academic Research Consortium consensus document was reached in 12.6%.Our results show that TAVI performed under local anaesthesia with only mild analgesic medication and under fluoroscopic guidance is feasible, with good outcome comparable to published data.

View details for DOI 10.1136/heartjnl-2013-304918

View details for Web of Science ID 000336893400007

View details for PubMedID 24459291

Abstract

Coronary calcifications are a marker of coronary atherosclerosis. The role of coronary calcium scoring (CS) as part of the initial evaluation of patients with suspected coronary heart disease (CHD) is controversially discussed. The primary goal of this study was to characterize the coronary calcium distribution in this particular patient population. In a second step, we aimed to establish a possible clinical implication using CS for the diagnosis of CHD.Calcium scoring procedure was performed by either using a multidetector or a dual-source computed tomographic scanner. All patients underwent invasive coronary angiography (ICA) as the current criterion standard for CHD detection. A total of 4,137 (2,780 men, mean age 60.5 12.4 years) consecutive patients were included.Mean CS was 288 446 (range 0-5,252). Overall coronary artery calcifications significantly increased with patients' age. In 2,048 patients (mean CS 101 239, range 0-5252), significant CHD (50% stenosis) was excluded by ICA (1,939 patients without calcifications). In remaining 2,089 patients (51%, mean CS 607 821, range 0-5,252), significant CHD was documented leading to intervention in 732 patients. A threshold of zero calcifications (existence of calcified tissue) had the best overall sensitivity and negative predictive value with 99%. Overall specificity with 34% and overall positive predictive value with 24% were rather low.Coronary calcium scoring is able to exclude significant CHD in patients with suspected CHD with a high negative predictive value and, therefore, possibly reduce the number of invasive diagnostic examinations. Because of the low specificity and positive predictive value, CS cannot be used to indicate ICA.

View details for DOI 10.1016/j.ahj.2013.12.011

View details for Web of Science ID 000333170900021

View details for PubMedID 24655707

Abstract

To determine the feasibility of a dynamic CT angiography-protocol with regard to simultaneous assessment of renal anatomy and function.7 healthy potential kidney donors (58 7 years) underwent a dynamic computed tomography angiography (CTA) using a 128-slice CT-scanner with continuous bi-directional table movement, allowing the coverage of a scan range of 18 cm within 1.75 sec. Twelve scans of the kidneys (n = 14) were acquired every 3.5 seconds with the aim to simultaneously obtain CTA and renal function data. Image quality was assessed quantitatively (HU-measurements) and qualitatively (grade 1-4, 1 = best). The glomerular filtration rate (GFR) was calculated by a modified Patlak method and compared with the split renal function obtained with renal scintigraphy.Mean maximum attenuation was 464 58 HU, 435 48 HU and 277 29 HU in the aorta, renal arteries, and renal veins, respectively. The abdominal aorta and all renal vessels were depicted excellently (grade 1.0). The image quality score for cortex differentiation was 1.6 0.49, for the renal parenchyma 2.4 0.49. GFR obtained from dynamic CTA correlated well with renal scintigraphy with a correlation coefficient of r = 0.84; P = 0.0002 (n = 14). The average absolute deviation was 1.6 mL/min. The average effective dose was 8.96 mSv.Comprehensive assessment of renal anatomy and function is feasible using a single dynamic CT angiography examination. The proposed protocol may help to improve management in case of asymmetric kidney function as well as to simplify evaluation of potential living kidney donors.

View details for DOI 10.1371/journal.pone.0091774

View details for Web of Science ID 000332842400127

View details for PubMedID 24618919

Abstract

We investigated the impact of the diameter of the valvuloplasty balloon (VB) used for predilation before transcatheter aortic valve implantation (TAVI) on atrioventricular block formation with consecutive need for permanent pacemaker (PP) implantation.TAVI was performed in 269 consecutive patients using the CoreValve prosthesis (Medtronic) via transfemoral access under local anaesthesia with mild analgesic medication. After exclusion of 32 patients with previously implanted PP, 237 patients were included in a retrospective analysis of the impact of VB size on subsequent PP incidence. Implantation success rate was 99.3%. Periprocedural mortality was 0%, and 30-day mortality was 5.9%. PP implantation after TAVI was required by 21.1%. Of 114 patients treated by 25 mm balloon valvuloplasty, a PP was implanted in 27.1%. In 123 patients, who were treated by VB with a 23 mm diameter, the PP implantation rate decreased to 15.4% (p=0.04). In univariate analysis, larger VB size resulted in a greater prevalence of PP implantation after TAVI. After adjustment by multivariate analysis for baseline clinical and operative characteristics, VB size remained an independent predictor of PP implantation.Moderate balloon predilation in patients undergoing TAVI with the Medtronic CoreValve prosthesis reduces the PP rate without affecting procedural success.

View details for DOI 10.4244/EIJV9I10A195

View details for Web of Science ID 000333444300006

View details for PubMedID 24561731

Abstract

This study evaluates calcium scoring (CS) and computed tomography angiography (MSCTA) in patients >50 years with chest-pain submitted to the emergency department utilising CS as a "diagnostic filter" upfront. Results of CS and MSCTA performed by a 64-slice CT scanner were compared to invasive coronary angiography (ICA). 289 consecutive symptomatic patients (185 men, mean age 71.3 6.4 years) were included. In patients with CS = 0 (Group I; n = 60) or CS > 400 (Group III; n = 95) we refrained from MSCTA, whereas patients with CS 1-400 (Group II; n = 134) underwent subsequent MSCTA. ICA detected significant coronary artery disease (CAD) in 162 patients (56.1%; male 98). None of Group I-patients showed CAD, but in Group III CAD prevalence increased to 82.1%. In Group II, MSCTA correctly identified 177/190 significantly diseased vessel segments. Compared to CS alone, our approach increased sensitivity to 98.1% (+1.8%), specificity to 82.6% (+27.5%) and negative predictive value (NPV) to 97.2% (+5.1%) as well as positive predictive value to 87.8% (+14.6%), respectively. Overall DA was 91.3%. Stratification of symptomatic patients into three different risk groups according to CS results with concomitantly increasing disease prevalence is possible. Zero calcium was found to exclude significant CAD, but needs further evaluation. Still server calcifications impair image quality in MSCTA. Thus direct referral to ICA might be a reasonable approach in case of high CS. In patients with intermediate CS, MSCTA is able to rule out significant CAD with a high NPV.

View details for DOI 10.1007/s10554-013-0292-9

View details for Web of Science ID 000330342800016

View details for PubMedID 24030295

Abstract

Coronary CT angiography (CCTA) is usually performed during breath holding to reduce motion artifacts caused by respiration. However, some patients are not able to follow the breathing commands adequately due to deafness, hearing impairment, agitation or pulmonary diseases. The aim of this study was to evaluate the potential of high-pitch CCTA in free breathing patients when compared to breath holding patients.In this study we evaluated 40 patients (20 free breathing and 20 breath holding patients) with a heart rate of 60 bpm or below referred for CCTA who were examined on a 2nd generation dual-source CT system. Image quality of each coronary artery segment was rated using a 4-point grading scale (1: non diagnostic-4: excellent).Mean heart rate during image acquisition was 52 5 bpm in both groups. There was no significant difference in mean image quality, slightly favoring image acquisition during breath holding (mean image quality score 3.76 0.32 in breath holding patients vs. 3.61 0.45 in free breathing patients; p = 0.411). Due to a smaller amount of injected contrast medium, there was a trend for signal intensity to be slightly lower in free breathing patients, but this was not statistically significant (435 123 HU vs. 473 117 HU; p=0.648).In patients with a low heart rate who are not able to hold their breath adequately, CCTA can also be acquired during free breathing without substantial loss of image quality when using a high pitch scan mode in 2nd generation dual-source CT.

View details for DOI 10.1016/j.ejrad.2011.09.003

View details for Web of Science ID 000326683100051

View details for PubMedID 24075783

Abstract

To assess the benefit of quantitative computed tomography (CT) perfusion for differentiating acute tubular necrosis (ATN) and acute rejection (AR) in kidney allografts.Twenty-two patients with acute kidney allograft dysfunction caused by either AR (n=6) or ATN (n=16) were retrospectively included in the study. All patients initially underwent a multiphase CT angiography (CTA) protocol (12 phases, one phase every 3.5s) covering the whole graft to exclude acute postoperative complications. Multiphase CT dataset and dedicated software were used to calculate renal blood flow. Renal biopsy or clinical course of disease served as the standard of reference. Mean effective radiation dose and mean amount of contrast media were calculated.Renal blood flow values were significantly lower (P=0.001) in allografts undergoing AR (48.321ml/100ml/min) compared with those with ATN (77.521ml/100ml/min). No significant difference (P=0.71) was observed regarding creatinine level with 5.653.1mg/dl in AR and 5.31.9mg/dl in ATN. The mean effective radiation dose of the CT perfusion protocol was 13.65.2mSv; the mean amount of contrast media applied was 34.55.1ml. All examinations were performed without complications.CT perfusion of kidney allografts may help to differentiate between ATN and rejection. Quantitative CT perfusion of renal transplants is feasible. CT perfusion could help to non-invasively differentiate AR from ATN. CT perfusion might make some renal biopsies unnecessary.

View details for DOI 10.1007/s00330-013-2862-6

View details for Web of Science ID 000323056600015

View details for PubMedID 23660773

Abstract

Pericardial adipose tissue (PAT), a visceral fat depot surrounding the heart, serves as an endocrine active organ and is associated with inflammation. There is growing evidence that atrial fibrillation (AF) is linked with inflammation, which in turn can be a promoter of left atrial remodeling. The aim of this study was to evaluate a potential correlation of PAT to AF and left atrial structural remodeling represented by LA size.PAT was measured in 1,288 patients who underwent coronary artery calcium-scanning for coronary risk stratification. LA size was determined by two independent readers. Patients were subdivided into patients without AF, patients with paroxysmal and persistent AF.PAT was independently correlated with AF, persistent AF, and LA size (all p values <0.001). No association could be observed between paroxysmal AF and PAT. These associations persisted after multivariate adjustment for AF risk factors such as age, hypertension, valvular disease, heart failure, and body mass index (AF: OR 1.52, 95 % CI 1.15-2.00, p = 0.003; persistent AF: OR 2.58, 95 % CI 1.69-3.99, p = 0.001; LA size: regression coefficient 0.15 with 95 % CI 0.10-0.20, p < 0.001).PAT is associated with AF, in particular with persistent AF and LA size. These findings suggest that PAT could be an independent risk factor for the development of AF and for LA remodeling.

View details for DOI 10.1007/s00392-013-0566-1

View details for Web of Science ID 000321965200002

View details for PubMedID 23584714

Abstract

A 65-year-old male patient was considered inoperable by conventional means for a previous triple coronary artery bypass grafting with a patent in situ right internal mammary artery graft to the left anterior descending artery crossing the thorax at midline directly behind the sternum. Transcatheter aortic valve implantation failed due to loss of the prosthetic device in the left ventricular outflow tract. Mandatory conversion was accomplished by an inferior partial T-shape sternotomy and extracorporeal circulation draining from the right atrium and feeding into the right femoral artery. A conventional 27-mm aortic valve bioprosthesis was successfully implanted during deep hypothermic circulatory arrest. The patient recovered normally exhibiting no neurological or cardiocirculatory complications.

View details for DOI 10.1055/s-0032-1327762

View details for PubMedID 23344755

Abstract

To evaluate the diagnostic accuracy (DA) of CT-myocardial perfusion imaging (CT-MPI) and a combined approach with CT angiography (CTA) for the detection of haemodynamically relevant coronary stenoses in patients with both suspected and known coronary artery disease.Prospective, non-randomised, diagnostic study.Academic hospital-based study.65 patients (42 men age 70.49) with typical or atypical chest pain.CTA and CT-MPI with adenosine stress using a fast dual-source CT system. At subsequent invasive angiography, FFR measurement was performed in coronary arteries to define haemodynamic relevance of stenosis.We tried to correlate haemodynamically relevant stenosis (FFR<0.80) to a reduced myocardial blood flow (MBF) as assessed by CT-MPI and determined the DA of CT-MPI for the detection of haemodynamically relevant stenosis.Sensitivity and negative predictive value (NPV) of CTA alone were very high (100% respectively) for ruling out haemodynamically significant stenoses, specificity, Positive predictive value (PPV) and DA were low (43.8, 67.3 and 72%, respectively). CT-MPI showed a significant increase in specificity, PPV and DA for the detection of haemodynamically relevant stenoses (65.6, 74.4 and 81.5%, respectively) with persisting high sensitivity and NPV for ruling out haemodynamically relevant stenoses (97% and 95.5% respectively). The combination of CTA and CT-MPI showed no further increase in detection of haemodynamically significant stenosis compared with CT-MPI alone.Our data suggest that CT-MPI permits the detection of haemodynamically relevant coronary artery stenoses with a moderate DA. CT may, therefore, allow the simultaneous assessment of both coronary morphology and function.

View details for DOI 10.1136/heartjnl-2013-303794

View details for Web of Science ID 000320924100007

View details for PubMedID 23674364

Abstract

Purpose of the study was to compare radiological treatment response according to RECIST, Choi and volumetry in GIST-patients under 2nd-line-sunitinib-therapy and to correlate the results of treatment response assessment with disease-specific survival (DSS).20 patients (mean: 60.7 years; 12 male/8 female) with histologically proven GIST underwent baseline-CT of the abdomen under imatinib and follow-up-CTs 3 months and 1 year after change to sunitinib. 68 target lesions (50 hepatic, 18 extrahepatic) were investigated. Therapy response (partial response (PR), stable disease (SD), progressive disease (PD)) was evaluated according to RECIST, Choi and volumetric criteria. Response according to the different assessment systems was compared and correlated to the DSS of the patients utilizing Kaplan-Meier statistics.The mean DSS (in months) of the response groups 3 months after therapy change was: RECIST: PR (0/20); SD (17/20): 30.4 (months); PD (3/20) 11.6. Choi: PR (10/20) 28.6; SD (8/20) 28.1; PD (2/20) 13.5. Volumetry: PR (4/20) 29.6; SD (11/20) 29.7; PD (5/20) 17.2. Response groups after 1 year of sunitinib showed the following mean DSS: RECIST: PR (3/20) 33.6; SD (9/20) 29.7; PD (8/20) 20.3. Choi: PR (10/20) 21.5; SD (4/20) 42.9; PD (6/20) 23.9. Volumetry: PR (6/20) 27.3; SD (5/20) 38.5; PD (9/20) 19.3.One year after modification of therapy, only partial response according to RECIST indicated favorable survival in patients with GIST. The value of alternate response assessment strategies like Choi criteria for prediction of survival in molecular therapy still has to be demonstrated.

View details for DOI 10.1016/j.ejrad.2013.02.034

View details for Web of Science ID 000318908300018

View details for PubMedID 23518148

Abstract

A 77-year-old male patient was scheduled for transcatheter aortic valve implantation for symptomatic and severe aortic valve stenosis. Severe multidirectional kinking of the aorta based on aortic coarctation did not allow for the transfemoral, but only for the transapical approach. The procedure was complicated because of the technically challenging retrograde passage of the transfemorally inserted pig-tail catheter required for intraoperative angiography of the aortic root. Correct positioning of the pig-tail catheter into the ascending aorta was accomplished by use of a loop snare, which was advanced into the descending aorta via the antegrade route, passing the cardiac apex, the stenotic aortic valve, and the coarctation-associated kinking. The pig-tail catheter tip was manipulated into the loop snare, pulled traverse the coarctation, and released within the proximal ascending aorta. Subsequent procedures were uneventful and followed the standardized protocol. A 29 mm Edwards Lifescience transcatheter Sapien bioprosthesis was successfully implanted.

View details for DOI 10.1055/s-0031-1295575

View details for Web of Science ID 000320168400015

View details for PubMedID 22215496

Abstract

Purpose Computed tomography (CT) is increasingly being used for planning purposes prior to trans-arterial valve implantation (TAVI). High-pitch protocols using a 2nd generation dual-source CT (DSCT) allow for a comprehensive assessment of the aortic valve anulus, its distance to the coronary artery ostia, the aortic bulbus and the iliofemoral arteries with very low radiation exposure and low amount of contrast agent. The aim of this study was to evaluate the image quality of a comparable high-pitch scan mode in a modern single-source CT (SSCT) system. Methods 40 patients with severe symptomatic aortic valve stenosis have been examined for planning purposes prior to TAVI. The first 20 consecutive patients were examined with a 2nd generation DSCT system using a high-pitch scan mode (pitch value 3.4) and 60 ml of contrast agent. The second group of 20 consecutive patients were examined with a 128-slice SSCT system, using a high-pitch scan mode (pitch value of 1.7) and 60 ml of contrast agent. Image quality of the aortic valve, the ascending aorta, the coronary artery ostia, the iliofemoral arteries and overall image quality were graded in a blinded fashion using a 4-point-grading-scale. Furthermore, signal intensity and image noise were derived in the ascending aorta and in the ilio-femoral arteries. Results There was a minor but significant difference in the overall image quality score with lower image quality in SSCT (3.5 0.6) when compared to DSCT (3.85 0.4; p = 0.037). The mean image quality score was significantly higher in patients examined in DSCT when compared to SSCT regarding the evaluability of the coronary ostia (4.0 vs. 3.5; p < 0.01) and the image quality of the ascending aorta (4.0 vs. 3.5; p < 0.01). There was no significant difference in evaluation of the aortic valve and its anulus (3.85 for DSCT and 3.65 for SSCT; p = 0.149) and image quality of the iliofemoral arteries (3.65 for DSCT and 3.85 for SSCT; p = 0.140). Signal intensity and image noise did not differ significantly between both groups. Conclusions This study presents a novel high-pitch protocol for modern SSCT scanners, which allows CT angiography for TAVI planning with a similar radiation dose and contrast agent exposition and only small compromises in image quality compared to a high-pitch protocol on a DSCT scanner.

View details for DOI 10.1007/s10554-013-0182-1

View details for Web of Science ID 000321384900024

View details for PubMedID 23334190

Abstract

The purpose of this study was to determine the effectiveness of a radiation dose reduction strategy for CT angiography by the combination of higher iodine delivery rate and automated tube potential selection with adjusted reference values for tube current-exposure time product, as well as to measure the impact of this approach on image quality.One hundred consecutive patients underwent high-pitch CT angiography of the thorax and abdomen using either 90 mL of iomeprol 300 (n = 44, protocol A) or 90 mL of iomeprol 400 (n = 56, protocol B) at the same flow rate. Automated tube potential selection was used with reference tube current-time products of 330 mAs and 250 mAs for protocols A and B, respectively. Twenty vascular segments were analyzed for attenuation and image noise by two readers. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all segments. The dose-length product (DLP) was documented to calculate effective dose and was compared between protocols both globally and for body mass index (BMI) subgroups.There were no differences in sex, height, weight, or BMI between both groups. Images from patients scanned with protocol B showed higher levels of image noise but also higher signal in all vascular segments. As a result, there were no differences in SNR between both groups. Conversely, CNR was significantly higher for almost all vascular segments in the group scanned using protocol B. Furthermore, DLP was significantly lower when protocol B was used, particularly in patients with a BMI of less than 30.In CT angiography, a combination of higher iodine delivery rate and automated tube potential selection with adjusted reference values for the tube current-time product allows reductions in radiation dose by approximately 30% without compromising image quality.

View details for DOI 10.2214/AJR.12.9635

View details for Web of Science ID 000319447700012

View details for PubMedID 23701094

Abstract

Functional imaging in patients with suspected or known coronary artery disease (CAD) is crucial for the identification of patients who could benefit from coronary revascularization. Several studies demonstrated the high diagnostic accuracy of Single-photon-emission computed tomography myocardial perfusion imaging, stress perfusion magnetic resonance imaging, and of invasive FFR measurements for the detection of hemodynamic relevant stenosis. Cardiac computed tomography (CT) used to be limited to coronary angiography (CTA); current guidelines recommend CTA only for the exclusion of CAD. Technological advances now offer the possibility to assess myocardial perfusion by computed tomography (CT-MPI). Though different acquisition protocols and post-processing algorithms still have to be evaluated, initial clinical studies could already show a diagnostic accuracy comparable to the established imaging modalities. Thus, cardiac CT may offer a combined approach of anatomical and functional imaging. Beside the need for further studies, especially on the prognostic value of CT-MPI to stratify future cardiovascular events, the comparatively high radiation exposure and additional administration of contrast agent has to be taken in account.

View details for DOI 10.1007/s12350-013-9681-7

View details for Web of Science ID 000316187200015

View details for PubMedID 23479267

Abstract

CT-based myocardial perfusion imaging (CTP) has been shown to accurately detect myocardial perfusion defects when compared to SPECT. When performing single-phase first-pass stress CTP, timing is of major importance. The aim of this study was to provide guidance for optimal timing of single-phase first-pass stress CTP acquisitions. 16 patients (12 male, age, 69 8 years) with known or suspected coronary artery disease underwent invasive coronary angiography with fractional flow reserve (FFR) measurements using a pressure wire as well as a time-resolved CTP protocol under adenosine stress, performed on a dual-Source CT scanner over a period of 30 s. From the CTP data, time-attenuation curves have been determined both in known ischemic myocardium with a corresponding coronary artery stenosis as proven by a FFR below 0.75 in invasive coronary angiography, as well as in non-ischemic reference myocardium during pharmacological stress. Furthermore, contrast enhancement in the ascending aorta was determined. The time point for an optimal contrast (i.e., difference in Hounsfield Units, HU) between ischemic and normal myocardium was determined. Under pharmacological stress using adenosine, a maximum mean HU difference between ischemic and non-ischemic myocardium (17.7-22.5 HU) was observed 24-32 s after injection of contrast medium. The maximal attenuation difference between normal and ischemic myocardium ranged from 15 to 77 HU in the analyzed patient cohort. When applying a bolus-tracking technique with an automatic contrast detection in the proximal ascending aorta, the optimal time frame for stress CTP was between 8 and 16 s after contrast enhancement in the aorta exceeds 100 HU, or between 7 and 15 s using a threshold of 150 HU. For first-pass CT myocardial perfusion imaging there is a time frame of approximately 8 s for optimal differentiation of ischemic and non-ischemic myocardium, which will be helpful to optimize single-phase CTP scans.

View details for DOI 10.1007/s10554-012-0080-y

View details for Web of Science ID 000314285500020

View details for PubMedID 22714549

Abstract

Lipoprotein a (Lp(a)) has been recognized as a risk factor for both coronary heart diseases and for cardiovascular events. Coronary artery calcification (CAC) is a well proven marker for coronary artery disease and risk factor for cardiovascular events. Still there are conflicting data regarding the relationship of Lp(a) and CAC. We therefore wanted to evaluate the influence of Lp(a) on CAC.1560 European patients (1123 men, age 59.3 20.8 years) with typical or atypical chest pain underwent CAC scoring by a multi-slice CT-scanner, using a standard protocol. Blood samples were evaluated the same day using an automated particle enhanced immunoturbidimetric assay to determine Lp(a) serum levels.There was a positive correlation between CAC score, age, and common cardiovascular risk factors. Lp(a) serum levels were not associated with age but a positive correlation between Lp(a) serum levels and CAC was found. In the multivariate analysis age, diabetes, statin therapy, and Lp(a) could be identified as independent risk factors for CAC. (p<0.001). BMI, smoking, hypertension and LDL-C were not independently associated with CAC.Lp (a) could be identified as an independent predictor of CAC, a marker of coronary atherosclerosis. Further a positive correlation between increasing Lp (a) levels and CAC scores was found.

View details for DOI 10.1016/j.ejim.2012.08.014

View details for Web of Science ID 000312831000023

View details for PubMedID 23021791

Abstract

To compare radiation exposure and image quality of oncological staging multidetector CT (MDCT) examinations of the chest, abdomen and pelvis with and without iterative reconstruction (IR).40 patients with known malignancy underwent staging CT examinations at two time points. Both CT scans were performed on the same scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). For the baseline scan, the tube current-time product was set to 250 mAs [image reconstruction: filtered back projection (FBP)] and for the follow-up scan to 150 mAs [reconstruction: iterative reconstruction (IR)]. Effective radiation doses were estimated based on dose-length products for both baseline and follow-up. Noise measurements in defined regions were compared for FBP and IR. Images were also subjectively evaluated for image quality by three radiologists with different levels of experience.Dose reduction was 44.48.2% for reduced-dose CT scans with IR compared with baseline with FBP. Image noise was not significantly different between images reconstructed with FBP and IR. The subjective quality of standard-dose FBP images and reduced-dose iteratively reconstructed CT images were identical.Our results show the dose-reducing potential of IR of CT image data in oncological patients.The algorithm tested in the present scientific study allows a >45% dose reduction at maintained image quality.

View details for DOI 10.1259/bjr.20120224

View details for Web of Science ID 000315266900015

View details for PubMedID 23255541

Abstract

To evaluate the feasibility of the classification of endoleaks following endovascular aortic aneurysm repair using the time-to-peak of the contrast agent in CEUS examinations.In this retrospective study, a cohort of 171 patients with a total of 489 CEUS follow-up examinations after EVAR were included. In 254 of the 489 examinations, an endoleak was seen and the time-to-peak was measured in seconds. Existence of an endoleak was confirmed by CT as the gold standard.We evaluated 254 CEUS video sequences showing an endoleak out of a total of 489 examinations. Kruskal-Wallis test revealed with p = 0.001 differences between the single endoleak types based on the time to peak. Correction after Bonferroni showed significant differences between type Ia compared to Ib and to IIa over inferior mesenteric artery (IMA) and IIa over lumbar artery (LA). There are also disparities between type Ib and type IIa IMA and type III, furthermore between type IIa IMA compared to IIa LA and type III as well as type IIa LA matched to type III.CEUS is an important method for the follow-up after EVAR. The time-to-peak does not seem to be a useful additional feature in classifying endoleaks, although there are differences between the time-to-peak of the single endoleak types and it is possible to make an order of the different endoleak types referring to the mean values.

View details for DOI 10.3233/CH-131701

View details for PubMedID 23455839

Abstract

Surgical treatment of degenerated aortic bioprostheses is associated with an increased risk of morbidity and mortality, especially in elderly patients with significant co-morbidities. Therefore, transcatheter aortic valve implantation (TAVI) performed as valve in valve technique appears as an attractive alternative treatment option. We report of a case series of seven patients with dysfunctional bioprosthetic aortic heart valves who have been treated with TAVI via transfemoral access.Valve in valve implantation using the Edwards Sapien XT bioprostheses (Edwards Lifesciences LLC, Irvine, CA, USA) was performed in eight patients (3 men, 5 women, mean age 85.3 6.1 years) with a high operative risk (logistic euroSCORE 27.2 7.3). Six patients underwent TAVI because of high grade stenosis of the aortic bioprostheses, whereas two patients presented with high grade regurgitation. All patients suffered at least from NYHA class III dyspnea during admission. TAVI was successfully performed via transfemoral access under local anesthesia with mild analgesic medication in all cases. Mild aortic regurgitation occurred in three patients while no permanent pacemaker implantation was required. Major cardiac events or cerebrovascular events did not occur. One aneurysm spurium, with the need of one blood transfusion, occurred. All patients improved at least one NYHA class within 30 days.TAVI for degenerated aortic bioprostheses, using the Edwards Sapien XT valve via transfemoral access is a feasible option for patients at high surgical risk.

View details for DOI 10.1007/s00392-012-0488-3

View details for Web of Science ID 000311362800006

View details for PubMedID 22729757

Abstract

To evaluate diagnostic image quality of high-pitch dual source comprehensive cardiothoracic CT protocol in patients presenting with acute undifferentiated chest pain.Consecutive symptomatic subjects (n=51) with undifferentiated acute chest pain underwent ECG-synchronized high-pitch dual-spiral chest CT angiography (Definition Flash, Siemens Medical Solutions, 2 100 kVp or 2 120 kV if BMI>30, collimation: 128 0.6mm, pitch: 3.2). Independent investigators determined the image quality of each cardiac and pulmonary vessel segment, measured contrast-to-noise-ratio (CNR), and determined radiation exposure. In addition, the prevalence of CT findings (pulmonary embolism (PE), aortic dissection (AD) and significant coronary stenosis ( 50%)) was determined. Univariate and multivariate analysis were performed to determine the subpopulation with highest diagnostic quality.Among 51 subjects (66% male, average age: 63 15.8), the prevalence of positive CT findings was moderate (overall: 11.7%). Overall, image quality of the pulmonary, aortic and coronary vasculature was good (1.26 0.43 and CNR: 2.52) with an average radiation dose of 3.82 mSv and 3.2% of segments rated non-evaluable. The image quality was lowest in the coronary arteries (p=0.02), depending on the heart rate (r=0.52, p<0.001). In subjects with a heart rate of 65 bpm (n=30) subjective image quality and CNR of the coronary arteries were higher (1.6 0.5 vs. 2.1 0.5, p=0.03 and 1.21 0.3 vs. 1.02 0.3, p=0.05) with only 1.5% segments classified as non-evaluable.High-pitch dual-spiral comprehensive cardiothoracic CT provides low radiation exposure with excellent image quality at heart rates 65 bpm. In subjects with higher heart rates, image quality of the aortic and pulmonary vasculature remains excellent, while the assessment of the coronary arteries degrades substantially.

View details for DOI 10.1016/j.ejrad.2010.11.032

View details for Web of Science ID 000311340800007

View details for PubMedID 21196093

Abstract

Immediate and efficient risk stratification and management of patients with acute chest pain in the emergency department is challenging. Traditional management of these patients includes serial ECG, laboratory tests and further on radionuclide perfusion imaging or ECG treadmill testing. Due to the advances of multi-detector CT technology, dedicated coronary CT angiography provides the potential to rapidly and reliably diagnose or exclude acute coronary artery disease. Life-threatening causes of chest pain, such as aortic dissection and pulmonary embolism can simultaneously be assessed with a single scan, sometimes referred to as "triple rule out" scan. With appropriate patient selection, cardiac CT can accurately diagnose heart disease or other sources of chest pain, markedly decrease health care costs, and reliably predict clinical outcomes. This article reviews imaging techniques and clinical results for CT been used to evaluate patients with chest pain entering the emergency department.

View details for DOI 10.1016/j.ejrad.2011.05.038

View details for Web of Science ID 000311340800004

View details for PubMedID 21798681

Abstract

Present study evaluates clinical feasibility of cardiac dual-source computed tomography angiography (DSCTA) to detect significant coronary stenosis because of chronic allograft vasculopathy (CAV) after heart transplantation (HTX). An overall of 51 consecutive heart transplant recipients (43 men, 8 women, mean age: 52.3 13.6 years) underwent DSCTA 1 2 days before annual routine invasive coronary angiography (ICA). Three patients were excluded from further analysis. Total 714/717 (99.6%) segments in remaining 48 patients were depicted in diagnostic image quality by DSCTA with three vessel segments in two patients being additionally excluded because of motion artefacts. On a segment-based analysis, sensitivity, specificity, and diagnostic accuracy (DA) for detection of significant stenosis were calculated as 100%, 98.9% and 98.9% respectively. On a patient-based evaluation, sensitivity, specificity and DA were 100%, 86.0% and 93.0% respectively for remaining 46 patients. Negative predictive value (NPV) was 100%. DSCTA enables diagnosis and especially the exclusion of significant coronary artery stenosis in patients after HTX with a high NPV. The low rate of excluded vessel segments compared with former studies indicates improvement in image acquisition and robustness of latest scanner technology and thus may make subsequent annual invasive coronary angiography unnecessary.

View details for DOI 10.1111/j.1432-2277.2012.01536.x

View details for PubMedID 22816613

Abstract

There has been a lack of standardized workup guidelines for patients with congenital abnormal origin of a coronary artery from the opposite sinus (ACAOS). We aimed to evaluate the use of cardiac hybrid imaging using multi-detector row CT (MDCT) for coronary CT angiography (Coronary CTA) and stress-rest myocardial perfusion SPECT (MPS) for comprehensive diagnosis of symptomatic adult patients with ACAOS. Seventeen symptomatic patients (12 men; 54 13 years) presenting with ACAOS underwent coronary CTA and MPS. Imaging data were analyzed by conventional means, and with additional use of 3D image fusion to allocate stress induced perfusion defects (PD) to their supplying coronary arteries. An anomalous RCA arose from the left anterior sinus in eight patients, an abnormal origin from the right sinus was detected in nine patients (5 left coronary arteries, LCA and 4 LCx). Five of the 17 patients (29%) demonstrated a reversible PD in MPS. There was no correlation between the anatomical variants of ACAOS and the presence of myocardial ischemia. Image fusion enabled the allocation of reversible PD to the anomalous vessel in three patients (two cases in the RCA and the other in the LCA territory); PD in two patients were allocated to the territory of artery giving rise to the anomalies, rather than the anomalies themselves. In a small cohort of adult symptomatic patients with ACAOS anomaly there was no relation found between the specific anatomical variant and the appearance of stress induced myocardial ischemia using cardiac hybrid imaging.

View details for DOI 10.1007/s10554-011-9995-y

View details for Web of Science ID 000310166700016

View details for PubMedID 22147107

Abstract

Imaging-based monitoring of molecular therapies in oncology remains a challenge. Molecular therapies might have more pronounced effects on lesion density than on lesion size. We analyzed changes in lesion diameter and density in patients with metastasized renal cell cancer (mRCC) in the early follow-up of targeted therapy and compared size-based measurements according to Response Evaluation Criteria in Solid Tumors (RECIST) with size- and density-based response evaluations according to the Choi criteria.A total of 22 patients treated with sorafenib (800 mg/d) were retrospectively analyzed. Relative changes (in %) in the greatest diameter and density of defined neoplastic "target lesions" were determined 8 weeks and 1 year after start of therapy in relation to a pretherapeutic baseline investigation. Data were analyzed according to RECIST (ver. 1.0), and results were compared with the response assessment based on Choi. Median survival was determined for all subgroups according to Choi or RECIST at the 8-week and 1-year follow-up.Applying RECIST, 18 patients (82%) demonstrated stable disease (SD) 8 weeks after the start of targeted therapy, 3 patients (14%) partial response (PR), and 1 patient (4%) progressive disease (PD). Partial responders at 8 weeks had a median survival of 48 months. After 1 year, 59% of all patients still showed SD. Applying Choi, 15 patients (68%) showed PR 8 weeks after the start of therapy, 5 patients (23%) SD, and 2 patients (9%) PD. After 1 year, PR was still the predominant response group (64% of the patients). Partial responders after 8 weeks had a median survival of 18 months.Choi defined more patients as partial responders at early stages of therapy than RECIST, but this was not an effective selection for patients with prolonged median survival. Evaluation of a larger patient cohort will further clarify the role of combined size- and density-based follow-up strategies in targeted therapy of mRCC.

View details for DOI 10.1016/j.urolonc.2010.10.011

View details for Web of Science ID 000310095800024

View details for PubMedID 21865061

Abstract

We aimed to investigate the value of the hyperdense basilar artery (HBA) sign and of basilar artery (BA) attenuation measurements as predictors of basilar artery occlusion (BAO) on nonenhanced cranial CT (NECT).Forty-one consecutive patients with proven BAO in CT angiography, who had undergone NECT for initial evaluation (30 males, 11 females) were retrospectively included. Another 41 age-matched patients without BAO were included as a control group. The NECT scans of both groups were assessed by three independent blinded readers (staff, fellow, and resident) in a randomized reading order using a standardized semiquantitative questionnaire. Visual BA hyperdensity, including the presence of HBA sign (hyperdensity scores of 4 and 5/5), was assessed, quantitative BA attenuation was measured in a region of interest (ROI), and diagnosis of BAO was made before and after ROI measurements. For statistical analysis, multivariate mixed effects models, likelihood ratio tests, and receiver operating characteristics techniques were applied.HBA sign had a relatively low sensitivity (60.98-65.85%), specificity (70.73-90.24%), and accuracy (65.85-75.61%) for the presence/absence of BAO on NECT. Optimal cut-off points were 40-42 HU (sensitivity, 68.29-78.05%; specificity, 75.61-82.93%; accuracy, 74.39-80.49%).In basilar artery occlusion, quantitative measurement of BA attenuation can slightly improve the diagnostic predictiveness of NECT. However, even with optimal cut-off values, the sensitivity is too low to serve as the sole diagnostic decision-making tool.

View details for DOI 10.1007/s00234-011-0887-6

View details for Web of Science ID 000301791000005

View details for PubMedID 21584673

Abstract

We sought to determine whether radiation dose can be reduced and image quality improved in computed tomography (CT) images of the brain that were acquired with automated exposure control (AEC), organ-based tube current modulation (TCM), multiband filtration (MBF), and iterative reconstruction in image space (IRIS).An Alderson-Rando-phantom, equipped with thermoluminescent dosimeters, was used to determine the radiation exposure of organs within the head and neck by different CT brain scan modes. We measured the noise and signal-to-noise ratios and subjectively graded quality criteria in different territories of the brain in spiral CT images of 150 patients. We also derived the radiation exposure from the patient protocols.In the phantom, AEC and TCM reduced the radiation exposure of the lenses, cerebrum, cerebellum, and thyroid gland by 41.9%, 34.5%, 30.5%, and 34.9%, respectively. Brain CT scans from patients investigated with AEC, TCM, MBF, and IRIS were found to have significantly better image quality than with conventional filtered back projection. In addition, the CT dose index and dose-length product were significantly lower with AEC, TCM, MBF, and IRIS by 24.1% and 20.2%, respectively.The combination of AEC, TCM, MBF, and IRIS improves image quality while radiation exposure can be reduced, particularly in dose-sensitive organs, such as the lenses and thyroid gland.

View details for DOI 10.1097/RLI.0b013e31823a86d5

View details for Web of Science ID 000300637900008

View details for PubMedID 22293512

Abstract

In this study, we show the use of three-dimensional printing models for preoperative planning of transcatheter valve replacement in a patient with an extreme porcelain aorta. A 70-year-old man with severe aortic stenosis and a porcelain aorta was referred to our center for transcatheter aortic valve replacement. Unfortunately, the patient died after the procedure because of a potential ischemic event. Therefore, we decided to fabricate three-dimensional models to evaluate the potential effects of these constructs for previous surgical planning and simulation of the transcatheter valve replacement.

View details for DOI 10.1016/j.athoracsur.2011.09.031

View details for Web of Science ID 000299540200005

View details for PubMedID 22269765

Abstract

Pericardial adipose tissue (PAT) is associated with coronary artery plaque accumulation and the incidence of coronary heart disease. We evaluated the possible incremental prognostic value of PAT for future cardiovascular events.145 patients (94 males, age 60 10 years) with stable coronary artery disease underwent coronary artery calcification (CAC) scanning in a multislice CT scanner, and the volume of pericardial fat was measured. Mean observation time was 5.4 years.34 patients experienced a severe cardiac event. They had a significantly higher CAC score (1,708 2,269 vs. 538 1,150, p < 0.01), and the CAC score was highly correlated with the relative risk of a future cardiac event: 2.4 (1.8-3.7; p = 0.01) for scores >400, 3.5 (1.9-5.4; p = 0.007) for scores >800 and 5.9 (3.7-7.8; p = 0.005) for scores >1,600. When additionally a PAT volume >200 cm(3) was determined, there was a significant increase in the event rate and relative risk. We calculated a relative risk of 2.9 (1.9-4.2; p = 0.01) for scores >400, 4.0 (2.1-5.0; p = 0.006) for scores >800 and 7.1 (4.1-10.2; p = 0.005) for scores >1,600.The additional determination of PAT increases the predictive power of CAC for future cardiovascular events. PAT might therefore be used as a further parameter for risk stratification.

View details for DOI 10.1159/000337083

View details for Web of Science ID 000305377600002

View details for PubMedID 22516924

Abstract

To study the feasibility of an optimized multiphase renal-CT-angiography (MP-CTA) protocol in patients with history of renal transplantation compared with Doppler-ultrasound (DUS).36 Patients underwent both DUS and time-resolved, MP-CTA (12 phases), with a mean contrast-volume of 34.45.1 ml. Quality of MP-CTA was assessed quantitatively (vascular attenuation) and qualitatively (grades 1-4, 1=best). For the assessment of clinical value of MP-CTA, cases were grouped into normal, macrovascular (arterial/venous) and microvascular complications (parenchymal perfusion defect). DUS served as the standard of reference.Using the best of 12 phases in each patient, optimal attenuation was 353111 HU, 33798 HU and 16451 HU in the iliac arteries, renal arteries, and renal veins, respectively. Mean image quality was 1.10.3 (n=36) and 2.10.6 (n=30) for the transplant renal arteries and veins, respectively. Six renal veins were non-diagnostic in MP-CTA. In 36 patients, MP-CTA showed 13 vascular complications and 10 parenchymal perfusion defects. DUS was not assessable in eight patients. Overall, MP-CTA showed 15 cases with pathology (42%) not identifiable with DUS. The mean effective radiation dose of the MP-CTA protocol was 13.55.2 mSv.MP-CTA can be sufficiently performed with reduced contrast volume at reasonable radiation dose in renal transplant patients, providing substantially higher diagnostic yield than DUS.

View details for DOI 10.1016/j.ejrad.2010.10.010

View details for Web of Science ID 000296763300080

View details for PubMedID 21111553

Abstract

Cardiac allograft vasculopathy (CAV) still limits survival after heart transplantation. Currently available noninvasive tests are of inferior value to detect CAV, and thus invasive coronary angiography (ICA) is frequently performed. Cardiac dual-source computed tomography calcium scoring (DSCTCS) offers the possibility to detect coronary calcifications, which might serve as a noninvasive marker of CAV. This study sought to evaluate its clinical feasibility.One hundred sixty-one patients (130 men; 31 women; mean age: 50.512.1 years) underwent DSCTCS 12 days before annual routine ICA. Mean posttransplant time was 73.749.6 months. The results of DSCTCS were compared with ICA.In 100 patients (85 men; 15 women; mean age: 51.512.3 years), coronary calcifications were detected, and in 61 patients (45 men; 16 women; mean age: 49.011.7 years), coronary calcifications were excluded. ICA excluded CAV in 82 patients (63 men; 19 women; mean age: 48.611.9 years). In 79 patients (67 men; 12 women; mean age: 52.512.2 years), CAV was detected of whom 11 patients needed stent implantation. No statistically significant difference of DSCTCS in patients without (17.229.5; range: 0-190) and with CAV (33.466.8; range: 0-385) was observed (P=0.133). Moreover, 4 of 11 (36.4%) severely diseased patients had a calcium score of zero. Sensitivity, specificity, negative predictive value, and positive predictive value for CAV detection (calcium score threshold >0) was calculated as 72.2%, 47.6%, 47.7%, and 57.0%, respectively. Diagnostic accuracy was 59.6%.DSCTCS is not a valuable noninvasive modality for CAV detection and thus not recommended in clinical practice. Moreover, we hypothesize that it represents preexisting or de novo traditional coronary atherosclerosis than CAV.

View details for DOI 10.1097/TP.0b013e318225281d

View details for Web of Science ID 000293501300023

View details for PubMedID 21705970

View details for DOI 10.1007/s12350-011-9384-x

View details for Web of Science ID 000293138900027

View details for PubMedID 21567284

Abstract

To compare a contrast agent with high iodine concentration with an iso-osmolar contrast agent for coronary dual-source computed tomography angiography (DS-CTA), and to assess whether the contrast agent characteristics may affect the diagnostic quality of coronary DS-CTA.Patients were randomized to receive either 80 mL of iodixa:nol-320 (Visipaque, GE Healthcare, Chalfont St. Giles, United Kingdom) or iomeprol-400 (Iomeron, Bracco Imaging SpA, Milan, Italy) at 5 mL/s. Mean, minimum, maximum heart rate, and its variation (max-min) were assessed during calcium scoring scan and coronary DS-CTA. Three off-site readers independently evaluated the image sets in terms of technical adequacy, reasons for inadequacy, vessel visualization, diagnostic confidence (based on a 5-point scale), and arterial contrast opacification in Hounsfield units (HUs).Ninety-six patients were included in the final evaluation. No significant differences were observed for pre- and postdose heart rate values for iomeron-400 compared with iodixanol-320, and changes in heart rate variation were also not significantly different (-2.3 11.7 vs. -2.5 7.3 bpm, P > 0.1). Contrast measurements in all analyzed vessels were significantly higher for iomeprol-400 (mean, 391.5-441.4 HU) compared with iodixanol-320 (mean, 332.3-365.5 HU, all P 0.0038). There was no significant difference in qualitative visualization of coronary arteries (mean scores, 4.3-4.5 for iomeprol, 4.1-4.3 for iodixanol, P = 0.15-0.28), or in diagnostic confidence scores. HU were inversely correlated with the number of insufficiently opacified segments (all readers P 0.0006).The high-iodine concentration contrast medium iomeprol-400 demonstrated significant benefit for coronary arterial enhancement compared with the iso-osmolar contrast medium iodixanol-320 when administered at identical flow rates and volumes for coronary DS-CTA. In addition, higher enhancement levels were found to be associated with lower numbers of inadequately visualized segments. Finally, observed mean heart rate changes after intravenous contrast injection were generally small during the examination and comparable for both agents.

View details for DOI 10.1097/RLI.0b013e31821c7ff4

View details for Web of Science ID 000291249400007

View details for PubMedID 21577124

Abstract

The aim of the study was to assess the performance and diagnostic value of a dual energy CT approach to reduce metal artefacts in subjects with metallic implants.31 patients were examined in the area of their metallic implants using a dual energy CT protocol (filtered 140 kVp and 100 kVp spectrum, tube current relation: 3:1). Specific post-processing was applied to generate energies of standard 120 and 140 kVp spectra as well as a filtered 140 kVp spectrum with mean photon energies of 64, 69 and 88 keV, respectively, and an optimized hard spectrum of 95-150 keV. Image quality and diagnostic value were subjectively and objectively determined.Image quality was rated superior to the standard image in 29/31 high energy reconstructions; the diagnostic value was rated superior in 27 patients. Image quality and diagnostic value scores improved significantly from 3.5 to 2.1 and from 3.6 to 1.9, respectively. In several exams decisive diagnostic features were only discernible in the high energy reconstructions. The density of the artefacts decreased from -882 to -341 HU.Dual Energy CT with specific postprocessing can reduce metal artefacts and may significantly enhance diagnostic value in the evaluation of metallic implants.

View details for DOI 10.1007/s00330-011-2062-1

View details for Web of Science ID 000290962800009

View details for PubMedID 21249370

Abstract

The purpose of this study was to determine whether rotational C-arm computed tomography (CT) allows visualization of liver metastases and adds relevant information for radioembolization (RE) treatment planning. Technetium angiography, together with C-arm CT, was performed in 47 patients to determine the feasibility for RE. C-arm CT images were compared with positron emission tomography (PET)/CT images for the detection of liver tumors. The images were also rated according one of the following three categories: (1) images that provide no additional information compared with DSA alone; (2) images that do provide additional information compared with DSA; and (2) images that had an impact on eligibility determination for and planning of the RE procedure. In all patients, 283 FDG-positive liver lesions were detected by PET. In venous contrast-phase CT, 221 (78.1%) and 15 (5.3%) of these lesions were either hypodense or hyperdense, respectively. In C-arm CT, 103 (36.4%) liver lesions were not detectable because they were outside of either the field of view or the contrast-enhanced liver segment. Another 25 (8.8%) and 98 (34.6%) of the liver lesions were either hyperdense or presented primarily as hypodense lesions with a rim enhancement, respectively. With PET/CT as the standard of reference, venous CT and C-arm CT failed to detect 47 (16.6%) and 57 (20.1%) of all liver lesions, respectively. For RE planning, C-arm CT provided no further information, provide some additional information, or had an impact on the procedure in 20 (42.5%), 15 (31.9%) and 12 (25.6%) of patients, respectively. We conclude that C-arm CT may add decisive information in patients scheduled for RE.

View details for DOI 10.1007/s00270-010-9897-8

View details for Web of Science ID 000290730300016

View details for PubMedID 20512333

Abstract

Advanced gastrointestinal stromal tumours (GISTs) are treated with tyrosine kinase inhibitors, which also have antiangiogenic properties. Dual-energy CT (DECT) allows to acquire semi-quantitative iodine images which might correlate with blood pool and tumor vascularity. In this feasibility-study, we correlated lesional iodine uptake estimations in correlation to tumor size changes under targeted therapy as first step in the evaluation of dedicated DECT based strategies for monitoring molecular therapies in GIST.48 tumor lesions in 18 patients with metastasized histologically proven GIST under tyrosine kinase inhibitor (TKI) therapy were analyzed. Patients were examined with a dual-source CT in dual-energy mode (Voltage tube A: 80 kV, tube B: 140 kV). Using the dual-energy software virtual unenhanced, selective iodine (overlay) and mixed CT numbers (similar to CT numbers at 120 kV) of lesions were calculated. The largest diameter of each lesion on cross-sectional axial images was measured. The mean difference of overlay CT numbers in the baseline and follow-up examinations was calculated and this marker of lesional iodine uptake was compared to lesional size changes under molecular therapy.Utilizing the cut-off value 15 HU of change in overlay, DECT allowed to identify lesions with a stable, increased or decreased lesional iodine uptake with corresponding typical lesion size change patterns after 3 months of targeted therapy: 30 lesions had no significant change of overlay CT numbers (OL) (mean: -2.4 HU) or lesion size (mean: +1.5%). A strong decline of the OL (mean: - 24 HU) in 13 lesions was combined with a pronounced growth (mean: + 26%). 5 lesions showed a strong increase of the absolute OL (mean: + 23 HU) associated with a moderate increase in size (+ 8%).Determination of the overlay CT number with DECT enables to stratify metastases with stable, increasing or decreasing iodine uptake over time with -in our collective- typical lesion size change patterns. Investigation of a larger patient cohort, comparison to histology, alternate imaging biomarkers and correlatrion to long-term response will further clarify the significance of these findings for monitoring targeted therapies in GIST.

View details for Web of Science ID 000289770000009

View details for PubMedID 21342100

Abstract

The aim of this pilot study was the evaluation of CT perfusion patterns in metastatic GIST lesions under specific molecular therapy with sunitinib or imatinib both in responders and non-responders.24 patients with metastatic GIST under tyrosine kinase inhibition were retrospectively evaluated. A total of 46 perfusion and venous phase CT scans were acquired. Volume of distribution, blood flow, blood volume, permeability and hepatic perfusion index measurements of metastatic lesions were carried out. Lesions were classified as "good response" or "poor response" to therapy, and perfusion parameters were compared for these two types of lesions.24 patients were evaluated. In the extrahepatic abdominal lesions (N = 15), good responders showed significant lower perfusion values than poor responders (volume of distribution: 3.3 2.0 vs. 13.0 1.8 ml/100ml, p = 0.001). The same tendency was observed in intrahepatic lesions (N = 31) (liver volume of distribution: 2.1 0.3 vs. 7.1 1.3 ml/100ml, p = 0.003); (hepatic perfusion index: 24.3 7.9 vs. 76.1 1.5%, p = 0.0001).Our data indicate that there are characteristic perfusion patterns of metastatic GIST lesions showing a good or poor response to molecular pharmacotherapy. Perfusion should be further evaluated in cross-sectional imaging studies as a possible biomarker for treatment response in targeted therapies of GIST.

View details for DOI 10.1016/j.ejrad.2009.07.031

View details for Web of Science ID 000286623100022

View details for PubMedID 19720488

Abstract

The present study aimed to distinguish responders to cardiac resynchronization therapy (CRT) from nonresponders, using electrocardiogram-gated 18F-FDG PET/CT.Seven consecutive CRT nonresponders were included in the study, along with 7 age- and sex-matched CRT responders, serving as reference material. Therapy response was defined as clinical improvement (1 New York Heart Association class) and evidence of reverse remodeling. Besides PET/CT, we measured brain natriuretic peptide levels and assessed dyssynchrony using transthoracic echocardiography.Compared with nonresponders, CRT responders showed significant differences in the declines of left-ventricular end-systolic volume and brain natriuretic peptide and in left-ventricular dyssynchrony (global left-ventricular entropy), extent of the myocardial scar burden, and biventricular pacemaker leads positioned within viable myocardial regions. Among the nonresponders, further therapy management was guided by the PET/CT results in 4 of 7 patients.Cardiac hybrid imaging using gated 18F-FDG PET/CT enabled the identification of potential reasons for nonresponse to CRT therapy, which can guide subsequent therapy.

View details for DOI 10.2967/jnumed.110.078709

View details for Web of Science ID 000285686400016

View details for PubMedID 21149479

Abstract

The aim of this study was to test the feasibility of time-resolved computed tomography angiography (TR-CTA) for use in the lower leg.Fifty-nine patients with suspected peripheral arterial occlusive disease were examined with a standard CTA (S-CTA) of the lower run-off and with an additional TR-CTA of the calves (12 phases; 2.5 s/phase, 80 kV, 120 mAs, volume of contrast medium 50 mL, flow rate 5.0 mL/s). For seven lower-leg artery segments, arterial contrast and the presence of venous overlay were tested for S-CTA and TR-CTA. Stenoses were classified on a three-point scale separately for S-CTA and TR-CTA, and diagnostic confidence for stenosis assessment was evaluated for both datasets. Contrast arrival times and HU values were evaluated in patients with asymmetric proximal stenoses.TR-CTA resulted in significantly higher contrast enhancement (P < 0.0001) and less venous overlay as compared to S-CTA (P < 0.05). Diagnostic confidence for stenosis rating was significantly higher in TR-CTA (P < 0.0001). Asymmetric proximal stenoses lead to significantly delayed and diminished contrast enhancement on the stenotic side.TR-CTA of the calves is feasible and provides higher enhancement and higher diagnostic confidence as compared to monophasic CTA of the lower legs.

View details for DOI 10.1007/s00330-010-1861-0

View details for Web of Science ID 000284117000013

View details for PubMedID 20589380

Abstract

Concerns have been raised regarding the increasing radiation exposure associated with cardiac computed tomography (CT). Traditional cardiac CT imaging techniques comprise simultaneous recording of the electrocardiogram signal combined with continuous slow-pitch spiral/helical scan acquisition with a relatively high incident radiation dose. Because of the increasing number of cardiac CT studies and further anticipated growth, the contribution of cardiac CT to radiation exposure of the population is not negligible. With growing radiation dose awareness, a variety of strategies have been developed aimed at improving the dose efficiency of electrocardiogram-synchronized cardiac CT acquisition techniques. Recent innovations have demonstrated that the radiation dose at cardiac CT can be substantially reduced without detrimental effects on diagnostic image quality. This study reviews currently available strategies for successfully reducing radiation dose in cardiac CT.

View details for DOI 10.1097/RTI.0b013e3181ec9096

View details for Web of Science ID 000281114500005

View details for PubMedID 20711037

Abstract

To determine the feasibility of a dynamic CT angiography-protocol in regard to simultaneous assessment of morphology and function.Fourteen patients with renal graft dysfunction received a dynamic computed tomography angiography (CTA) using a 128-slice CT-scanner with continuous bi-directional table movement, allowing to cover a scan range of 18 cm within 1.75 seconds. Twelve scans of the entire kidney were acquired every 3.5 seconds with the aim to simultaneously obtain CTA and renal function data. The glomerular filtration rate (GFR) was calculated by a modified Patlak method and compared with creatinine-based formulas (MDRD 4 and endogenous creatinine clearance), that served as reference standard.GFR obtained from dynamic CTA correlates well with the GFR derived by creatinine-based formulas with a correlation coefficient of r = 0.8986; P < 0.0001. The average absolute deviation was 8.1 mL/min. The mean amount of contrast medium required was 35 mL. The average effective dose was 13.8 mSv.Dynamic CTA offers the possibility to determine the GFR and thus facilitates simultaneous assessment of morphology and function. Additionally, our dynamic CTA-protocol helps to significantly reduce the amount of contrast medium, which is beneficial for patients with impaired renal function.

View details for DOI 10.1097/RLI.0b013e3181e332d0

View details for Web of Science ID 000279394300004

View details for PubMedID 20479647

Abstract

To evaluate the diagnostic accuracy of dual-energy CT (DECT) in renal mass characterization using a single-phase acquisition.A total of 202 patients (148 males, 54 females; 63 +/- 13 years) with ultrasound-based suspicion of a renal mass underwent unenhanced single energy and nephrographic phase DECT on a dual source scanner (Siemens Somatom Definition Dual Source, n = 174; Somatom Definition Flash, n = 28). Scan parameters for DECT were: tube potential, 80/100 and 100/Sn140 kVp; exposure, 404/300 and 96/232 effective mAs; collimation, 14 x 1.2/32 x 0.6 mm. Two abdominal radiologists assessed DECT and SECT image quality and noise on a 5-point visual analogue scale. Using solely the DE acquisition including virtual nonenhanced (VNE) and color coded iodine images that enable direct visualization of iodine, masses were characterized as benign or malignant. In a second reading session after 34 to 72 (average: 55) days, the same assessment was again performed using both the true nonenhanced (TNE) and nephrographic phase scans thereby simulating conventional single-energy CT. Sensitivities, specificities, diagnostic accuracies, and interpretation times and were recorded for both reading paradigms. Dose reduction of a single-phase over a dual-phase protocol was calculated. Results were tested for statistical significance using the paired Wilcoxon signed rank test and student t test. Differences in sensitivities were tested for significance using the McNemar test.Of the 202 patients, 115 (56.9%) underwent surgical resection of renal masses. Histopathology showed malignancy in 99 and benign tumors in 18 patients, in 48 patients (23.7%), follow-up imaging showed size stability of lesions diagnosed as benign, and 37 patients (18.3%) had no mass. Based on DECT only, 95/99 (96.0%) patients with malignancy and 96/103 (93.2%) patients without malignancy were correctly identified, for an overall accuracy of 94.6%. The dual-phase approach identified 96/99 (97.0%) and 98/103 (95.1%), accuracy 96.0%, P > 0.05 for both. Mean interpretation time was 2.2 +/- 0.8 minutes for DECT, and 3.5 +/- 1.0 minutes for the dual-phase protocol, P < 0.001. Mean VNE/TNE image quality was 1.68 +/- 0.65/1.30 +/- 0.59, noise was 2.03 +/- 0.57/1.18 +/- 0.29, P < 0.001 for both. Omission of the true unenhanced phase lead to a 48.9 +/- 7.0% dose reduction.DECT allows for fast and accurate characterization of renal masses in a single-phase acquisition. Interpretation of color coded images significantly reduces interpretation time. Omission of a nonenhanced acquisition can reduce radiation exposure by almost 50%.

View details for DOI 10.1097/RLI.0b013e3181e33189

View details for Web of Science ID 000279394300006

View details for PubMedID 20498609

Abstract

Recent technical developments have led to an extension of perfusion computed tomography (PCT) scan range to cover nearly the entire brain and to reconstruct time resolved (4d) CT-angiography (CTA) datasets from the PCT data. The purpose of this study was to compare the results of simulated standard PCT and extended PCT with 4d-CTA.Extended multimodal stroke CT (unenhanced cranial CT, CTA, and PCT) was acquired in 72 patients. PCT images with a scan coverage of 9.6 cm in the z-axis, simulated 2 cm PCT images at the level of the basal ganglia comparable to standard PCT, standard supra-aortic CTA, and 4d-CTA images were reconstructed. Two readers assessed the PCT image quality as well as pathologic findings in extended and simulated PCT, CTA, and 4d-CTA. The brain was divided into 4 axial segments. The independent samples t test was applied to test differences between data for significance.In 75.0% of all patient exams, pathologic findings were observed in the PCT; these were located in 138 brain segments. In 24.1% of all 54 exams with pathologic PCT findings, the pathology would have been missed on standard PCT. The longer scan coverage resulted in a different final diagnosis in 34.7% of all exams. Quality of the PCT parameter maps was on average very good both for the supratentoric and the infratentoric brain areas (4.28 and 4.18, respectively, on a 5-point scale). In 90% of all exams with pathologic changes in the CTA, these abnormalities were also noted on 4d-CTA. In only 2.8% of all cases, the additional time resolution of the 4d-CTA provided additional information.Extending the scan coverage of PCT from 2 cm to 9.6 cm led to an augmentation of clinically important information in the imaging of acute stroke.

View details for DOI 10.1097/RLI.0b013e3181e1956f

View details for Web of Science ID 000279394300001

View details for PubMedID 20458248

Abstract

New generation Dual Source computed tomography (CT) scanners offer different x-ray spectra for Dual Energy imaging. Yet, an objective, manufacturer independent verification of the dose required for the different spectral combinations is lacking. The aim of this study was to assess dose and image noise of 2 different Dual Energy CT settings with reference to a standard chest scan and to compare image noise and contrast to noise ratios (CNR). Also, exact effective dose length products (E/DLP) conversion factors were to be established based on the objectively measured dose.An anthropomorphic Alderson phantom was assembled with thermoluminescent detectors (TLD) and its chest was scanned on a Dual Source CT (Siemens Somatom Definition) in dual energy mode at 140 and 80 kVp with 14 x 1.2 mm collimation. The same was performed on another Dual Source CT (Siemens Somatom Definition Flash) at 140 kVp with 0.8 mm tin filter (Sn) and 100 kVp at 128 x 0.6 mm collimation. Reference scans were obtained at 120 kVp with 64 x 0.6 mm collimation at equivalent CT dose index of 5.4 mGy*cm. Syringes filled with water and 17.5 mg iodine/mL were scanned with the same settings. Dose was calculated from the TLD measurements and the dose length products of the scanner. Image noise was measured in the phantom scans and CNR and spectral contrast were determined in the iodine and water samples. E/DLP conversion factors were calculated as ratio between the measured dose form the TLDs and the dose length product given in the patient protocol.The effective dose measured with TLDs was 2.61, 2.69, and 2.70 mSv, respectively, for the 140/80 kVp, the 140 Sn/100 kVp, and the standard 120 kVp scans. Image noise measured in the average images of the phantom scans was 11.0, 10.7, and 9.9 HU (P > 0.05). The CNR of iodine with optimized image blending was 33.4 at 140/80 kVp, 30.7 at 140Sn/100 kVp and 14.6 at 120 kVp. E/DLP conversion factors were 0.0161 mSv/mGy*cm for the 140/80 kVp protocol, 0.0181 mSv/mGy*cm for the Sn140/100 kVp mode and 0.0180 mSv/mGy*cm for the 120 kVp examination.Dual Energy CT is feasible without additional dose. There is no significant difference in image noise, while CNR can be doubled with optimized dual energy CT reconstructions. A restriction in collimation is required for dose-neutrality at 140/80 kVp, whereas this is not necessary at 140 Sn/100 kVp. Thus, CT can be performed routinely in Dual Energy mode without additional dose or compromises in image quality.

View details for DOI 10.1097/RLI.0b013e3181df901d

View details for Web of Science ID 000278000200009

View details for PubMedID 20404737

Abstract

To determine the practicability and potential dose saving of an imaging algorithm incorporating a pulsing scheme applying systolic data acquisition at heart rates >75 beats per minute (bpm).Patients clinically referred for coronary computed tomography angiography (CTA) underwent cardiac CTA using either a diastolic pulsing window (30-70%) or a narrow systolic pulsing window (150 ms at 300 ms). Independent investigators retrospectively determined image quality (1, excellent, to 5, unreadable) and derived effective radiation exposure.Among all 101 subjects (62 +/- 2 years, 59% male) the predicted decrease in the best reconstruction interval for diastolic phases was 12 ms per 1 bpm [95% confidence interval (CI): -13.5 to -11.2] and -1.9 ms for systolic phases (95% CI: -3.2 to -0.62, p = 0.004), independent of age, gender and body mass index (BMI). The systolic pulsing strategy in 47 subjects (23 subjects >75 bpm) resulted in significantly lower radiation exposure (4.97 +/- 2.3 vs 9.38 +/- 5.5 mSv, p < 0.001 for systolic versus diastolic, respectively), whereas there was no difference with respect to image quality or heart rate (p = 0.65 and p = 0.74, respectively).Our results suggest that a systolic window for tube current modulation in subjects with higher heart rates represents a reliable tool to ensure high image quality at significantly lower dose in patients undergoing routine cardiac CTA.

View details for DOI 10.1007/s00330-009-1680-3

View details for Web of Science ID 000277200500005

View details for PubMedID 20033181

Abstract

The radiation exposure of a dual-source-64-channel multi-detector-computed-tomography-scanner (Somatom-Defintion, Siemens, Germany) was assessed in a phantom-study performing coronary-CT-angiography (CTCA) in comparison to patients' data randomly selected from routine scanning.240 CT-acquisitions of a computed tomography dose index (CTDI)-phantom (PTW, Freiburg, Germany) were performed using a synthetically generated Electrocardiography (ECG)-signal with variable heart rates (30-180 beats per minute (bpm)). 120 measurements were acquired using continuous tube-output; 120 measurements were performed using ECG-synchronized tube-modulation. The pulsing window was set at minimum duration at 65% of the cardiac cycle between 30 and 75 bpm. From 90-180 bpm the pulsing window was set at 30-70% of the cardiac cycle. Automated pitch adaptation was always used. A comparison between phantom CTDI and two patient groups' CTDI corresponding to the two pulsing groups was performed.Without ECG-tube-modulation CDTI-values were affected by heart-rate-changes resulting in 85.7 mGray (mGy) at 30 and 45 bpm, 65.5 mGy/60 bpm, 54.7 mGy/75 bpm, 46.5 mGy/90 bpm, 34.2 mGy/120 bpm, 27.0 mGy/150 bpm and 22.1 mGy/180 bpm equal to effective doses between 14.5 mSievert (mSv) at 30/45 bpm and 3.6 mSv at 180 bpm. Using ECG-tube-modulation these CTDI-values resulted: 32.6 mGy/30 bpm, 36.6 mGy/45 bpm, 31.4 mGy/60 bpm, 26.8 mGy/75 bpm, 23.7 mGy/90 bpm, 19.4 mGy/120 bpm, 17.2 mGy/150 bpm and 15.6 mGy/180 bpm equal to effective doses between 5.5 mSv at 30 bpm and 2.6 mSv at 180 bpm. Significant CTDI-differences were found between patients with lower/moderate and higher heart rates in comparison to the phantom CTDI-results.Dual source CTCA is particularly dose efficient at high heart rates when automated pitch adaptation, especially in combination with ECG-based tube-modulation is used. However in clinical routine scanning for patients with higher heart rates and corresponding enlarged pulsing window a significant different dose resulted.

View details for DOI 10.1016/j.ejrad.2009.06.001

View details for PubMedID 19608362

Abstract

The aim of this study was to test the feasibility and the additional value of time-resolved computed tomography angiography (CTA) of the aorta, using multiple low-dose phases.Twenty-two consecutive patients underwent a time-resolved CTA protocol (TR-CTA) of the aorta, either for follow-up of endovascular aneurysm repair (EVAR) or aortic dissection, using a CT scanner with the possibility of bidirectional table movements for dynamic CT imaging (Siemens Definition AS+; 12 phases, temporal resolution 2.5 s/scan, 80 kVp, 120 mAs/rot, scan range 27 cm, 60 mL; Imeron 400, flow 5.0 mL/s). The patients had previously undergone standard CTA (120 kVp, 100 mL contrast agent). Standard CTA after EVAR and aortic dissection were triphasic and biphasic protocols, respectively. Effective radiation dose and maximum Hounsfield unit values were compared between the TR-CTA and standard CTA. Image quality was rated for TR-CTA.Fifteen patients underwent TR-CTA for follow-up after EVAR; 4 were examined for follow-up after dissection and 3 for both, that is, aortic dissection treated with an endovascular stent. Mean effective dose of TR-CTA for the scan range of 27 cm (15.3+/-1.1 mSv) was comparable with the biphasic standard CTA protocols (16.2+/-2.4 mSv; P=0.29). Triphasic protocols resulted in 23.7+/-4.9 mSv (P<0.0001). Hounsfield unit values were not significantly different. Most of the examinations (91%) were fully evaluable, whereas 9% were of limited evaluability because of high image noise. None of the examinations was nondiagnostic.TR-CTA consisting of multiple low-dose phases leads to a clear depiction of the angiographic information and is feasible for follow-up after EVAR and aortic dissection. Considering the limited scan range, radiation dose is comparable with the standard biphasic CTA protocol, but dynamic information may provide additional information.

View details for DOI 10.1097/RTI.0b013e3181d9c9de

View details for Web of Science ID 000278199600012

View details for PubMedID 20463535

Abstract

To detail the principles of using model-based determination of regional myocardial blood flow (MBF) by computed tomography (CT) and demonstrate its in vivo applicability.Dual-source CT was performed with a dynamic protocol comprising acquisition with alternating table positions in ECG-triggered end-systolic timing every second for 30 s. The results of two reconstructions were merged into one final image stack (coverage 73 mm), with low spatial frequency components from a 360 degrees reconstruction and high spatial frequency components from a dual-source cardiac partial image reconstruction. A parametric deconvolution technique was used to fit the time-attenuation curves (TAC), the maximum slope of which was used to derive MBF.One study participant underwent dynamic myocardial stress perfusion imaging (9.6 mSv) followed by invasive coronary angiography and measurement of fractional flow reserve as the gold standard. MBF was 159 ml/100 ml/min in the non-ischaemic anterolateral and 86 ml/100 ml/min in the inferoseptal ischaemic wall.This first evaluation indicates that mathematical modelling of voxel TACs can potentially be used to quantify differences in MBF in a clinical setting. If confirmed in feasibility studies, cardiac CT may allow for parallel assessment of morphology and haemodynamic relevance of coronary artery disease.

View details for DOI 10.1007/s00330-010-1715-9

View details for Web of Science ID 000276425700018

View details for PubMedID 20333388

Abstract

To compare true and "virtual" noncontrast images derived from dual-energy CT examinations in patients after endovascular repair of aortic aneurysms.Seventy dual-energy CT examinations were performed on a dual-source CT scanner with a single-energy noncontrast scan and a dual-energy acquisition in venous phase. True and virtual noncontrast images were compared regarding image quality, calcifications in true noncontrast images, subtraction of calcification in virtual noncontrast images, and acceptance levels by two radiologists. Presence of endoleaks was assessed on venous-phase images and on virtual or true noncontrast images. In addition, the acceptance of color-coded images, in which iodine information is colored, was assessed. Possible dose reduction of a single-phase dual-energy examination protocol was compared with a standard biphasic examination protocol.Twenty-four endoleaks were detected and correctly classified with both approaches. Mean image quality was rated good for virtual noncontrast images (1.97 +/- 0.99) and excellent for true noncontrast images (1.16 +/- 0.37; P< .0001). Ninety-four percent of virtual noncontrast images were rated as diagnostic, and 80% of all true noncontrast images showed calcifications within the aneurysm. Subtraction of calcification in virtual noncontrast images was classified as none (30%), minimal (40%), moderate (24%), or severe (6%). Eighty-three percent of color-coded images were rated as fully diagnostic, 11% were accepted with restrictions, and 6% were nondiagnostic. Possible dose reduction of a single-phase dual-energy protocol, compared with a standard biphasic protocol, was 44%.Dual-energy CT makes a reliable detection of endoleaks feasible in a single acquisition. This provides a potential dose reduction for patients who have to undergo lifelong follow-up examinations after endovascular aneurysm repair.

View details for DOI 10.1016/j.jvir.2009.10.040

View details for Web of Science ID 000277367700001

View details for PubMedID 20097097

Abstract

High radiation doses remain a drawback of current triple-rule-out computed tomography (CT) protocols. With dual source CT, a new high-pitch dual spiral technique offers the possibility to acquire an Electrocardiography (ECG)-gated-synchronized dataset of the whole chest in less than 1 second. The aim of this study was to compare the dose of such a protocol to a standard, nongated chest scan and to a conventional, retrospectively ECG-gated triple-rule-out protocol. Also, the efficacy and dose of this dual spiral protocol was to be compared in patients examined with this high-pitch technique and matched controls scanned with the conventional technique.An anthropomorphic Alderson Rando phantom was equipped with thermoluminescent detectors and scanned with the high-pitch protocol (Siemens Somatom Definition Flash; 2 x 120 kVp, 426 mAseff, 128 x 0.6 mm collimation, pitch 3.2), the nongated chest scan (same scanner; 120 kVp, 160 mAseff, 128 x 0.6 mm, pitch 1.2; equivalent Computed Tomography Dose Index (CTDI) of 7.12 mGy), and the conventional gating technique (Siemens Somatom Definition; 120 kVp, 560 mAseff with ECG pulsing interval at 30%-70% of the R-R cycle, 64 x 0.6 mm, pitch 0.3). Noise was measured in air, central and peripheral soft tissue of the phantom. Conversion factors were determined based on the measured dose and the dose-length products of the scanner. The protocol was then applied with ethics committee approval in 31 patients suffering from acute chest pain. The 120 mL of contrast material (Ultravist 370, Bayer Schering Pharma) was applied at 5 mL/s. Dose was calculated based on the dose-length products and the conversion factor. Image quality was assessed by 2 readers for aorta, pulmonary arteries, and coronary arteries. The results were compared with matched controls scanned with the conventional ECG gating technique and non-ECG gated thorax scans.The dose determined with thermoluminescent dosimeters measurements amounted to 2.65, 2.68, and 19.27 mSv, respectively, for the dual spiral technique, the standard chest scan, and the conventional retrospective technique. There was no significant difference in image noise. Respective conversion factors were 0.0186, 0.0188, and 0.0180 mSv/mGy x cm. In the patient examinations, dose was 4.08 +/- 0.81 mSv with the high-pitch protocol compared with 20.4 +/- 5.3 mSv in the matched controls with the conventional technique, and 4.40 +/- 0.83 mSv for the non-ECG gated thorax scan. Scan times were 0.7 +/- 0.1 seconds for the high-pitch scan and 15 +/- 3 seconds for the conventional chest pain scan. Aorta and pulmonary arteries were depicted in diagnostic quality in both groups. About 84.7% of coronary artery segments were rated as diagnostic in the high-pitch exams (95.4% below 65 bpm and only 72.8% in higher heart rates), whereas 92.9% were diagnostic with the conventional approach.The high-pitch dual spiral technique requires only about one-fifth of the dose of conventional ECG gated triple-rule-out protocols, thus matching that of a standard nongated chest scan. With less than 1 second, the scan time is very short. This protocol can be recommended for patients with unclear chest pain with rhythmic heart rates below 65 bpm.

View details for Web of Science ID 000273959500002

View details for PubMedID 20027121

Abstract

We report discordant imaging findings of a small persistent type II endoleak in a 72-year-old man who had undergone endovascular aneurysm repair (EVAR) of an abdominal aortic aneurysm. Although the aneurysm was growing in size digital subtraction angiography could not detect an endoleak, but time-resolved CT-angiography and contrast enhanced ultrasound did detect a small type II endoleak.

View details for DOI 10.3233/CH-2010-1283

View details for Web of Science ID 000279013800003

View details for PubMedID 20571226

Abstract

In many patients, unheralded myocardial infarction associated with a mortality of approximately 20% is the first manifestation of coronary artery disease. Approximately 40% of the population is considered to have a moderate midterm risk of 10% to 20%. Any of the stratification schemes suffers from a lack of accuracy to correctly determine the risk, and uncertainty exists regarding how to treat individuals who have been identified to be at intermediate risk. Other tools providing information about the necessity to reassure or to treat these patients are warranted. Currently, the assessment of the atherosclerotic plaque burden by CT may be able provide valid information for this cohort. This article discusses the potential value and limitations of cardiac CT for evaluating coronary atherosclerotic plaque.

View details for DOI 10.1016/j.ccl.2009.06.013

View details for Web of Science ID 000270873600009

View details for PubMedID 19766918

Abstract

Myocardial infarction results as a consequence of atherosclerotic plaque rupture, with plaque stability largely depending on the lesion forming extracellular matrix components. Lipid enriched non-calcified lesions are considered more instable and rupture prone than calcified lesions. Matrix metalloproteinases (MMPs) are extracellular matrix degrading enzymes with plaque destabilisating characteristics which have been implicated in atherogenesis. We therefore hypothesised MMP-1 and MMP-9 serum levels to be associated with non-calcified lesions as determined by CT-angiography in patients with coronary artery disease.260 patients with typical or atypical chest pain underwent dual-source multi-slice CT-angiography (0.6-mm collimation, 330-ms gantry rotation time) to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed or non-calcified.In multivariable regession analysis, MMP-1 serum levels were associated with total plaque burden (OR: 1.37 (CI: 1.02-1.85); p < 0.05) in a model adjusted for age, sex, BMI, classical cardiovascular risk factors, hsCRP, adiponectin, pericardial fat volume and medication. Specification of plaque morphology revealed significant association of MMP-1 serum levels with non-calcified plaques (OR: 1.16 (CI: 1.0-1.34); p = 0.05) and calcified plaques (OR: 1.22 (CI: 1,03-1.45); p < 0.05) while association with mixed plaques was lost in the fully adjusted model. No associations were found between MMP9 serum levels and total plaque burden or plaque morphology.MMP-1 serum levels are associated with total plaque burden but do not allow a specification of plaque morphology.

View details for DOI 10.1186/1475-2840-8-50

View details for Web of Science ID 000270752500001

View details for PubMedID 19751510

Abstract

To evaluate the incremental prognostic value of coronary artery calcification (CAC) scoring over single photon emission computed tomographic (SPECT) myocardial perfusion imaging in long-term prognosis and survival of patients with stable coronary artery disease (CAD).All patients provided written informed consent to undergo CAC scoring according to a protocol that was approved by the local clinical institutional review board. Over a median follow-up time of 5.4 years, 260 patients with stable CAD were followed up for severe cardiac events (cardiac death or nonfatal myocardial infarction). CAC scanning and SPECT myocardial perfusion imaging were performed at enrollment. Patients were stratified on the basis of well-established cutoff points for CAC score, summed stress score (SSS), and summed rest score (SRS). Kaplan-Meier survival curves and the Cox proportional hazards model were used.CAC score and SRS were identified as the only independent predictors of event-free survival. Patients with perfusion abnormalities at rest (SRS > or = 2), a CAC score greater than 400, or severe perfusion abnormalities under stress (SSS > or = 13) were identified as having significantly increased risk for subsequent severe cardiac events (P = .023, .0095, and .007, respectively). In addition, a CAC score greater than 400 offered incremental prognostic value over the scintigraphic scores alone (P = .028 with an SSS > 8; P = .008 with an SRS > or = 2).CAC score and SRS were identified as independent predictors of severe cardiac events during long-term follow-up of patients with known CAD. CAC scores imparted superior risk stratification information as compared with SPECT myocardial perfusion imaging results alone.

View details for DOI 10.1148/radiol.2531082137

View details for Web of Science ID 000270809500008

View details for PubMedID 19703866

Abstract

The goal of our study was to compare a prospective triggering (PT) CT technique with retrospectively gated (RG) CT techniques in coronary computed tomographic angiograms (CCTA) with respect to image quality and radiation dose. Sixty consecutive patients were enrolled. CCTAs using the RG technique were obtained with a dual-source 64-slice CT system in 40 patients, using ECG-triggered tube current modulation, with either a broad pulsing window at 30-80% of the RR interval (group RGb, 20 patients, heart rate > 70 bpm) or a small pulsing window at 70% (group RGs, 20 patients, heart rate < 70 bpm). The other 20 patients underwent CCTA using the PT technique on a 128-slice CT system (group PT, heart rate < 70 bpm). All images were evaluated by two observers for quality on a three-point scale, with 1 being excellent and 3 being insufficient. The effective radiation dose was calculated for each patient. The average image quality score was 1.5 +/- 0.6 for PT, 1.35 +/- 0.5 for RGs and 1.65 +/- 0.5 for RGb. The mean effective dose for RGb was 9 +/- 4 mSv, for RGs 7 +/- 3 mSv and for PT 3 +/- 1 mSv. This represents a 57% dose reduction for PT compared with RGs and a 67% dose reduction for PT compared with RGb. In conclusion, in selected patients CCTA with the PT technique offers adequate image quality with a significantly lower radiation dose compared with CCTA using RG techniques.

View details for DOI 10.1007/s00330-009-1411-9

View details for Web of Science ID 000268544000007

View details for PubMedID 19415293

Abstract

So far C-arm CT images were predominantly used for a precise guidance of an endovascular or intra-arterial therapy. A novel combined 3D-navigation C-arm system now also allows cross-sectional and fluoroscopy controlled interventions. Studies have reported about successful CT-image guided navigation with C-arm systems in vertebroplasty. Insertion of the radiofrequency ablation probe is also conceivable for lung and liver tumors that had been labelled with lipiodol. In the future C-arm CT based navigation systems will probably allow simplified and safer complex interventions and simultaneously reduce radiation exposure.

View details for DOI 10.1007/s00117-009-1866-3

View details for Web of Science ID 000269911700009

View details for PubMedID 19701622

Abstract

To qualitatively and quantitatively compare virtual nonenhanced (VNE) data sets derived from dual-energy (DE) computed tomography (CT) with true nonenhanced (TNE) data sets in the same patients and to calculate potential radiation dose reductions for a dual-phase renal multidetector CT compared with a standard triple-phase protocol.This prospective study was approved by the institutional review board; all patients provided written informed consent. Seventy one men (age range, 30-88 years) and 39 women (age range, 22-87 years) underwent preoperative DE CT that included unenhanced, DE nephrographic, and delayed phases. DE CT parameters were 80 and 140 kV, 96 mAs (effective). Collimation was 14 x 1.2 mm. CT numbers were measured in renal parenchyma and tumor, liver, aorta, and psoas muscle. Image noise was measured on TNE and VNE images. Exclusion of relevant anatomy with the 26-cm field of view detector was quantified with a five-point scale (0 = none, 4 = >75%). Image quality and noise (1 = none, 5 = severe) and acceptability for VNE and TNE images were rated. Effective radiation doses for DE CT and TNE images were calculated. Differences were tested with a Student t test for paired samples.Mean CT numbers (+/- standard deviation) on TNE and VNE images, respectively, for renal parenchyma were 30.8 HU +/- 4.0 and 31.6 HU +/- 7.1, P = .29; liver, 55.8 HU +/- 8.6 and 57.8 HU +/- 10.1, P = .11; aorta, 42.1 HU +/- 4.1 and 43.0 HU +/- 8.8, P = .16; psoas, 47.3 HU +/- 5.6 and 48.1 HU +/- 9.3 HU, P = .38. No exclusion of the contralateral kidney was seen in 50 patients, less than 25% was seen in 43, 25%-50% was seen in 13, and 50%-75% was seen in four. Mean image noise was 1.71 +/- 0.71 for VNE and 1.22 +/- 0.45 for TNE (P < .001); image quality was 1.70 HU +/- 0.72 for VNE and 1.15 HU +/- 0.36 for TNE (P < .0001). In all but three patients radiologists accepted VNE images as replacement for TNE images. Mean effective dose for DE CT scans of the abdomen was 5.21 mSv +/- 1.86 and that for nonenhanced scans was 4.97 mSv +/- 1.43. Mean dose reduction by omitting the TNE scan was 35.05%.In patients with renal masses, DE CT can provide high-quality VNE data sets, which are a reasonable approximation of TNE data sets. Integration of DE scanning into a renal mass protocol will lower radiation exposure by 35%.

View details for DOI 10.1148/radiol.2522080557

View details for Web of Science ID 000268875900017

View details for PubMedID 19487466

Abstract

The purpose of this study was to assess the diagnostic accuracy of whole-body MRI (WB-MRI) at 1.5 T or 3 T compared with FDG-PET-CT in the follow-up of patients suffering from colorectal cancer. In a retrospective study, 24 patients with a history of colorectal cancer and suspected tumour recurrence underwent FDG-PET-CT and WB-MRI with the use of parallel imaging (PAT) for follow-up. High resolution coronal T1w-TSE and STIR sequences at four body levels, HASTE imaging of the lungs, contrast-enhanced T1w- and T2w-TSE sequences of the liver, brain, abdomen and pelvis were performed, using WB-MRI at either 1.5 T (n = 14) or 3 T (n = 10). Presence of local recurrent tumour, lymph node involvement and distant metastatic disease was confirmed using radiological follow-up within at least 5 months as a standard of reference. Seventy seven malignant foci in 17 of 24 patients (71%) were detected with both WB-MRI and PET-CT. Both investigations concordantly revealed two local recurrent tumours. PET-CT detected significantly more lymph node metastases (sensitivity 93%, n = 27/29) than WB-MRI (sensitivity 63%, n = 18/29). PET-CT and WB-MRI achieved a similar sensitivity for the detection of organ metastases with 80% and 78%, respectively (37/46 and 36/46). WB-MRI detected brain metastases in one patient. One false-positive local tumour recurrence was indicated by PET-CT. Overall diagnostic accuracy for PET-CT was 91% (sensitivity 86%, specificity 96%) and 83% for WB-MRI (sensitivity 72%, specificity 93%), respectively. Examination time for WB-MRI at 1.5 T and 3 T was 52 min and 43 min, respectively; examination time for PET-CT was 103 min. Initial results suggest that differences in accuracy for local and distant metastases detection using FDG-PET-CT and WB-MRI for integrated screening of tumour recurrence in colorectal cancer depend on the location of the malignant focus. Our results show that nodal disease is better detected using PET-CT, whereas organ disease is depicted equally well by both investigations.

View details for DOI 10.1007/s00330-008-1289-y

View details for Web of Science ID 000266085900010

View details for PubMedID 19190917

Abstract

In supraaortic vessels, bone subtracted maximum intensity projections make the evaluation of computed tomographic angiography (CTA) datasets easier and faster. Dual energy CT can be used for bone removal without user interaction. The purpose of this study was to compare the results of conventional and dual energy-based bone removal.Dual energy CT angiography of the supraaortic vessels was acquired in 30 patients at 140 and 80 kVp tube potential simultaneously. Thick images of 0.75 mm were reconstructed from both datasets, and an additional weighted average dataset using information from both tubes was calculated. Two readers independently assessed vessel delineation, completeness of bone removal, and vessel preservation, as well as adequacy for diagnostic evaluation after dual energy-based bone removal (DEBR) and conventional bone removal (CoBR). The Student t test and Wilcoxon rank sum test were applied to test differences between data for significance. Cohen's kappa-test was used to calculate the interobserver agreement.Of dual energy datasets DEBR 88.3% were rated as adequate for diagnostic evaluation compared with only 6.7% with CoBR, P < 0.001. Of DEBR (35%) contained all vessels and no bony structures, whereas all diagnostic CoBR still contained residual bone and showed partial vessel truncations. Vessel delineation was rated significantly better with DEBR. DEBR profited from stronger vascular enhancement, whereas it had no significant influence on CoBR. Reading times were 173 +/- 55 seconds with DEBR and 253 +/- 12 seconds with CoBR, P < 0.001, which corresponds to a reduction of 32%. Comparison of dual energy CTA versus single energy CTA showed a dose reduction of 29.0% to 43.7%.Dual Energy-based bone removal can remove bony structures from supraaortic CTA datasets without time-consuming user interaction. This leads to a significant reduction of reading time, radiation dose and improved vessel delineation.

View details for Web of Science ID 000265433800008

View details for PubMedID 19550378

Abstract

Pericardial fat as a visceral fat depot may be involved in the pathogenesis of coronary atherosclerosis. To gain evidence for that concept we sought to investigate the relation of pericardial fat volumes to risk factors, serum adiponectin levels, inflammatory biomarkers, and the quantity and morphology of coronary atherosclerosis.Using Dual source CT angiography pericardial fat volume and coronary atherosclerosis were assessed simultaneously. Plaques were classified as calcified, mixed, and noncalcified, and the number of affected segments served as quantitative score. Patients with atherosclerotic lesions had significant larger PAT volumes (226 cm3+/-92 cm3) than patients without atherosclerosis (134 cm3+/-56 cm3; P>0.001). No association was found between BMI and coronary atherosclerosis. PAT volumes >300 cm3 were the strongest independent risk factor for coronary atherosclerosis (odds ratio 4.1; CI 3.63 to 4.33) also significantly stronger compared to the Framingham score. We furthermore demonstrated that elevated PAT volumes are significantly associated with low adiponectin levels, low HDL levels, elevated TNF-alpha levels, and hsCRP.In the present study we demonstrated that elevated PAT volumes are associated with coronary atherosclerosis, hypoadiponectinemia, and inflammation and represent the strongest risk factor for the presence of atherosclerosis and may be important for risk stratification and monitoring.

View details for DOI 10.1161/ATVBAHA.108.180653

View details for Web of Science ID 000265230700028

View details for PubMedID 19229071

Abstract

Dual-energy computed tomography (CT) makes it possible to remove bones and intraluminal plaques from angiography datasets on the basis of spectral differentiation separating iodine from calcium. The objective of this study was to evaluate the feasibility and efficiency of this technique by comparing maximum intensity projections (MIP) created with different bone removal techniques: (a) dual-energy bone removal (DEBR); (b) purely software-based bone removal without manual corrections (SBBR - MC); and (c) manually corrected software-based bone removal (SBBR + MC). A further aim was to evaluate the dual-energy-based plaque removal tool.Fifty-one patients underwent dual-energy CT angiography of the lower-extremity arteries on a dual-source CT scanner. CT parameters were tube potentials, 140 and 80 kVp; exposure, 80 and 340 mAs/rot; and collimation, 14 x 1.2 mm. Bolus tracking was used in the descending aorta for timing (Ultravist 370). Bones were removed from the datasets using the 3 techniques and MIP datasets were generated. Two experienced radiologists assessed image quality ((1) correct removal of bones and preservation of vessels without artificial truncation, stenoses or occlusions of arteries; (2) minor errors with residual bone in the dataset or removal of side branches; (3) significant errors impeding diagnostic evaluation), number of vessel segmentation errors, and number of nonremoved bones. Additionally, time for MIP-generation was measured. The plaque removal tool was applied to DEBR MIPs and the outcome was rated as positive, neutral, or negative.DEBR showed better image quality than SBBR (P < 0.05; median image quality DEBR: 1; SBBR - MC: 3; SBBR + MC: 2). Less vessel segmentation errors occurred in DEBR (P < 0.05; median DEBR: 0; SBBR - MC: 5; SBBR + MC: 1). The number of nonremoved bones was not significantly different between DEBR and SBBR + MC, but significantly higher in SBBR - MC (median DEBR: 1; SBBR - MC: 2; SBBR + MC: 0). Time for generation of MIPs was lowest for SBBR - MC (P < 0.05), but also DEBR was significantly faster than manually corrected SBBR (DEBR: 160 +/- 16 seconds; SBBR - MC: 95 +/- 12 seconds; SBBR + MC: 373 +/- 69 seconds). The plaque removal tool lead to an improvement of image quality of the MIPs and a better depiction of the residual lumen in 43%.DEBR provides significant advantages, even over manually corrected SBBR. As it works completely automatically, it can effectively help to cope with the data load of CT angiography exams. Furthermore, it enables the removal of intraluminal plaques, which provides a benefit for the estimation of the residual lumen.

View details for Web of Science ID 000265433800006

View details for PubMedID 19346965

Abstract

Atherosclerosis is the primary cause of coronary artery disease (CAD). There is increasing recognition that lesion composition rather than size determines the acute complications of atherosclerotic disease. Low serum adiponectin levels were reported to be associated with coronary artery disease and future incidence of acute coronary syndrome (ACS). The impact of adiponectin on lesion composition still remains to be determined.We measured serum adiponectin levels in 303 patients with stable typical or atypical chest pain, who underwent dual-source multi-slice CT-angiography to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed or non-calcified. In bivariate analysis adiponectin levels were inversely correlated with total coronary plaque burden (r = -0.21, p = 0.0004), mixed (r = -0.20, p = 0.0007) and non-calcified plaques (r = -0.18, p = 0.003). No correlation was seen with calcified plaques (r = -0.05, p = 0.39). In a fully adjusted multivariate model adiponectin levels remained predictive of total plaque burden (estimate: -0.036, 95%CI: -0.052 to -0.020, p<0.0001), mixed (estimate: -0.087, 95%CI: -0.132 to -0.042, p = 0.0001) and non-calcified plaques (estimate: -0.076, 95%CI: -0.115 to -0.038, p = 0.0001). Adiponectin levels were not associated with calcified plaques (estimate: -0.021, 95% CI: -0.043 to -0.001, p = 0.06). Since the majority of coronary plaques was calcified, adiponectin levels account for only 3% of the variability in total plaque number. In contrast, adiponectin accounts for approximately 20% of the variability in mixed and non-calcified plaque burden.Adiponectin levels predict mixed and non-calcified coronary atherosclerotic plaque burden. Low adiponectin levels may contribute to coronary plaque vulnerability and may thus play a role in the pathophysiology of ACS.

View details for DOI 10.1371/journal.pone.0004733

View details for Web of Science ID 000265490800013

View details for PubMedID 19266101

View details for DOI 10.1161/CIRCULATIONAHA.108.777698

View details for PubMedID 19255355

Abstract

Despite constant improvements in scanner technology, reliable visualization of the coronary arteries with multislice spiral CT angiography (CTA) remains a major challenge in patients with atrial fibrillation (AF). The purpose of this study was to assess the image quality of coronary CT angiograms with coronary angiography, using a dual-source CT scanner (DSCT), comparing systolic and diastolic reconstruction techniques. Additionally, we sought to evaluate the diagnostic accuracy of DSCT with coronary angiography as the standard of reference.Sixty-eight patients with permanent AF were imaged on a DSCT system, with a temporal resolution of 82 milliseconds. The volume and flow rate of the contrast medium were adapted to the patient's body weight. The patients were not receiving any drugs for heart rate regulation. Each dataset was reconstructed at an absolute delay determined from the R wave at 300 milliseconds (ie, systolic reconstruction), as well as at 70% of the RR-cycle (diastolic reconstruction). Twenty-one patients underwent both DSCT and coronary angiography. Two blinded independent readers assessed significant stenoses (> or =50%), and image quality in terms of visibility and artifacts (4-point rating scale: 1 = excellent, 2 = good, 3 = poor, 4 = insufficient) on a per-patient- and a per-segment-based analysis (15-segment AHA model) for both the systolic and diastolic datasets. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated.: During 68 DSCT examinations, the mean heart rate ranged between 26 and 181 beats per minute (77 +/- 25). In the patient-based analysis, the image qualities of 64 of 68 CT angiograms (94%) were high enough to permit diagnosis, ie, 4 of 68 (6%) datasets were considered nonevaluable. Segment-based, a total of 898 of 979 coronary artery segments were rated as diagnostically evaluable (92%).In 57 of 68 evaluable patients (84%) the reconstructions in stole had fewer motion artifacts and thus showed superior image quality. The median image quality of all CT datasets was 2. In 21 patients undergoing both coronary angiography and DSCT, the overall sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of significant stenoses were 89% (16 of 18), 98% (260 of 265), 76% (16 of 21), and 99% (260 of 262), respectively, in the per-segment analysis (including 283 vessel segments) and 90% (9 of 10), 82% (9 of 11), 82% (9 of 11), and 90% (9 of 10), respectively, in the patient-based analysis.The image quality of coronary CT angiograms obtained with a DSCT is satisfactory in most patients with AF. In the majority of patients with high and irregular heart rate, the absolute forward approach with end-systolic reconstruction 300 milliseconds after the R-peak yield a higher image quality than diastolic reconstructions. As a result of a significant improvement in temporal resolution, DSCT coronary angiography is feasible in patients with AF and can be used to exclude coronary artery disease in this patient cohort.

View details for Web of Science ID 000263576800006

View details for PubMedID 19151607

Abstract

The aim of the study was to evaluate the diagnostic accuracy of multi-slice-computed tomography (MDCT) for the detection of vertebral metastases in comparison to magnetic resonance imaging (MRI).In a retrospective analysis, 639 vertebral bodies of 41 patients with various histologically confirmed primary malignancies were analysed. The MDCT-images were acquired on a 16/64-row-MDCT scanner (Siemens Somatom Sensation 16/64). MRI was performed on 1.5 T scanners (SIEMENS Symphony/Sonata). The MDCT- and MRI-images were evaluated separately by two experienced radiologists in a consensus reading. The combination of MDCT and MRI in an expert reading including follow-up examinations and/or histology as well as clinical data served as the gold standard.201/639 vertebral bodies were defined as metastatically affected by the gold standard. In MDCT 133/201 lesions, in MRI 198/201 lesions were detected. 68 vertebral bodies were false negative in MDCT, whereas 3 false negatives were found in MRI. 3 false positive results were obtained in MDCT, 5 in MRI. Sensitivity was significantly lower for MDCT (66.2%) than for MRI (98.5%) (p<0.0001). Specificity was not significantly different for both methods (MDCT: 99.3%; MRI: 98.9%). The diagnostic accuracy resulted in 88.8% for MDCT and 98.7% for MRI.Although 16/64-row-MDCT provides excellent image quality and a high spatial resolution in the assessment of bony structures, metastatic lesions without significant bone destruction may be missed. The diagnostic accuracy of MRI proved to be significantly superior to 16/64-row-MDCT for the detection of osseous metastases.

View details for DOI 10.1016/j.ejrad.2007.11.039

View details for Web of Science ID 000265370700033

View details for PubMedID 18191356

Abstract

This prospective trial was designed to compare the performance characteristics of five different screening tests in parallel for the detection of advanced colonic neoplasia: CT colonography (CTC), colonoscopy (OC), flexible sigmoidoscopy (FS), faecal immunochemical stool testing (FIT) and faecal occult blood testing (FOBT).Average risk adults provided stool specimens for FOBT and FIT, and underwent same-day low-dose 64-multidetector row CTC and OC using segmentally unblinded OC as the standard of reference. Sensitivities and specificities were calculated for each single test, and for combinations of FS and stool tests. CTC radiation exposure was measured, and patient comfort levels and preferences were assessed by questionnaire.221 adenomas were detected in 307 subjects who completed CTC (mean radiation dose, 4.5 mSv) and OC; 269 patients provided stool samples for both FOBT and FIT. Sensitivities of OC, CTC, FS, FIT and FOBT for advanced colonic neoplasia were 100% (95% CI 88.4% to 100%), 96.7% (82.8% to 99.9%), 83.3% (95% CI 65.3% to 94.4%), 32% (95% CI 14.9% to 53.5) and 20% (95% CI 6.8% to 40.7%), respectively. Combination of FS with FOBT or FIT led to no relevant increase in sensitivity. 12 of 45 advanced adenomas were smaller than 10 mm. 46% of patients preferred CTC and 37% preferred OC (p<0.001).High-resolution and low-dose CTC is feasible for colorectal cancer screening and reaches sensitivities comparable with OC for polyps >5 mm. For patients who refuse full bowel preparation and OC or CTC, FS should be preferred over stool tests. However, in cases where stool tests are performed, FIT should be recommended rather than FOBT.

View details for DOI 10.1136/gut.2008.156448

View details for Web of Science ID 000262369800018

View details for PubMedID 18852257

Abstract

The present study evaluates clinical feasibility of cardiac multidetector computed tomography angiography (MDCTA) to detect significant stenosis of coronary vessels due to transplant vasculopathy (TVP) after heart transplantation (HTx).Twenty-eight consecutive male HTx-recipients scheduled for their annual routine conventional coronary angiography (CCA) additionally underwent 64-slice MDCTA.Two patients were excluded from further MDCTA analysis. Out of 371 remaining coronary vessel segments evaluable by CCA, MDCTA was able to depict 302 (81.4%) in diagnostic image quality. On a segment based analysis, sensitivity, specificity, diagnostic accuracy (DA), negative predictive value (NPV), and positive predictive value (PPV) for detection of significant stenosis were calculated with 87.5%, 97.3%, 97.0%, 99.7%, and 46.7%, respectively. On a patient-based evaluation, sensitivity, specificity, DA, NPV, PPV were 100%, 81%, 84.6%, 100% and 55.6%, respectively. Evaluation of stenosis degree by MDCTA showed systematic overestimation of 4.4%. A moderate to good agreement comparing both modalities was found (Pearson's correlation coefficient: 0.64).High NPV suggesting 64-slice MDCTA being a reliable diagnostic tool for ruling out significant stenosis due to TVP in HTx patients. But its clinical value in these particular patients needs further investigation.

View details for DOI 10.1007/s10554-008-9343-z

View details for Web of Science ID 000262653600014

View details for PubMedID 18642098

Abstract

Purpose of this study was to determine the diagnostic value of dual energy CT in the assessment of pulmonary perfusion with reference to pulmonary perfusion scintigraphy. Thirteen patients received both dual energy CT (DECT) angiography (Somatom Definition, Siemens) and ventilation/perfusion scintigraphy. Median time between scans was 3 days (range, 0-90). DECT perfusion maps were generated based on the spectral properties of iodine. Two blinded observes assessed DECT angiograms, perfusion maps and scintigrams for presence and location of perfusion defects. The results were compared by patient and by segment, and diagnostic accuracy of DECT perfusion imaging was calculated regarding scintigraphy as standard of reference. Diagnostic accuracy per patient showed 75% sensitivity, 80% specificity and a negative predictive value of 66%. Sensitivity per segment amounted to 83% with 99% specificity, with 93% negative predictive value. Peripheral parts of the lungs were not completely covered by the 80 kVp detector in 85% of patients. CTA identified corresponding emboli in 66% of patients with concordant perfusion defects in DECT and scintigraphy. Dual energy CT perfusion imaging is able to display pulmonary perfusion defects with good agreement to scintigraphic findings. DECT can provide a pulmonary CT angiogram, high-resolution morphology of the lung parenchyma and perfusion information in one single exam.

View details for DOI 10.1016/j.ejrad.2008.07.031

View details for PubMedID 18775618

Abstract

To provide a novel, robust algorithm for classification of lung tissue depicted by multi-detector computed tomography (MDCT) based on the topology of CT-attenuation values and to compare discriminative results with densitometric methods. Two hundred seventy-five cubic volumes of interest (VOI, edge length 40 pixels) were obtained from MDCT chest CT (isotropic voxel size, edge length 0.6 mm) of 21 subjects with and without pathology (emphysema, fibrosis). All VOIs were visually consensus-classified by two radiologists. Texture features based on the Minkowski functionals (MF) as well as on the CT attenuation values are determined. Classification results of both approaches were assessed by receiver-operator characteristic and discriminant analysis. By densitometric (topological) parameters, normal and abnormal VOIs were distinguished with an area under the curve ranging from 0.78 to 0.85 (0.87 to 0.96). Correlation between both groups of parameters was non-significant (p > or = 0.36). By combined information of densitometric and topological quantities, the radiologists' ratings were reproduced for 92% of VOIs, ranging from 85.7% (fibrosis) to 98% (normal VOIs). Our method performs well for identification of VOIs containing abnormal lung-tissue. Combined information of densitometry and topology increases the number of correctly classified VOIs further. When extended to CT data depicting whole lungs, topological analysis may allow to enhance density-based analysis and improve monitoring texture changes with progression of pulmonary disease.

View details for DOI 10.1007/s00330-008-1082-y

View details for Web of Science ID 000260837300007

View details for PubMedID 18618121

Abstract

The gold standard for identification of the dead is the visual dental record. In this context, several authors emphasize computed tomography (CT) as valuable supportive tool for forensic medicine. However, studies focusing on diagnostic accuracy of post-mortem computed tomography (PMCT) are still missing. Therefore, the aim of this study was to compare diagnostic accuracy of the visual dental record and post-mortem computed tomography (PMCT) of the dentition for identification of the dead. Ten whole skulls were included into the study. The entire dentition of each skull was first examined with the visual dental record as a gold standard and second using dental PMCT scans, performed on a 64-multi-detector CT (MDCT). 3D reformations, multi-planar reformations (MPR), and CT-orthopantomography (OPG) were performed in the post-processing. All examinations were analyzed by three independent investigators regarding the criteria for identification of the dead, e.g., in case of disaster. PMCT for the dental identification of the dead was difficult to perform and time consuming. Due to dental overlays and corresponding artifacts, the definite periphery of the dental fillings/inlays was not accurately defined resulting in 2.9% incorrect and 64.1% false negative findings, especially synthetic inlays were hardly or not recognizable at all. For the identification of the dead especially in case of disasters with large numbers of victims, the visual dental record is still to be considered the gold standard. In the identification process itself, there is no room for error at all, although some non-concordant information may occur. Thus, PMCT should only be performed for identification in individual cases due to the relatively high error rate.

View details for DOI 10.1007/s00414-008-0274-y

View details for Web of Science ID 000259732400004

View details for PubMedID 18679703

Abstract

To establish an efficient prophylaxis of coronary artery disease reliable risk stratification is crucial, especially in the high risk population of patients suffering from diabetes mellitus. This prospective study determined the predictive value of coronary calcifications for future cardiovascular events in asymptomatic patients with diabetes mellitus.We included 716 patients suffering from diabetes mellitus (430 men, 286 women, age 55.2+/-15.2 years) in this study. On study entry all patients were asymptomatic and had no history of coronary artery disease. In addition, all patients showed no signs of coronary artery disease in ECG, stress ECG or echocardiography. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomograph. For quantification of coronary calcifications we calculated the Agatston score. After a mean observation period of 8.1+/-1.1 years patients were contacted and the event rate of cardiac death (CD) and myocardial infarction (MI) was determined.During the observation period 40 patients suffered from MI, 36 patients died from acute CD. The initial Agatston score in patients that suffered from MI or died from CD (475+/-208) was significantly higher compared to those without cardiac events (236+/-199, p<0.01). An Agatston score above 400 was associated with a significantly higher annualised event rate for cardiovascular events (5.6% versus 0.7%, p<0.01). No cardiac events were observed in patients with exclusion of coronary calcifications. Compared to the Framingham risk score and the UKPDS score the Agatston score showed a significantly higher diagnostic accuracy in the prediction of MI with an area under the ROC curve of 0.77 versus 0.68, and 0.71, respectively, p<0.01.By determination of coronary calcifications patients at risk for future MI and CD could be identified within an asymptomatic high risk group of patients suffering from diabetes mellitus. On the other hand future events could be excluded in patients without coronary calcifications.

View details for DOI 10.1186/1471-2261-8-27

View details for Web of Science ID 000266880000001

View details for PubMedID 18847481

Abstract

Posterior fossa artifacts constitute a characteristic limitation of cranial CT. To identify practical benefits and drawbacks of newer CT systems with reduced collimation in routine cranial imaging, we aimed to investigate image quality, posterior fossa artifacts and parenchymal delineation in non-enhanced CT (NECT) with 1-, 4-, 16- and 64-slice scanners using standard scan protocols. We prospectively enrolled 25 consecutive patients undergoing NECT on a 64-slice CT. Three groups with 25 patients having undergone NECT on 1-, 4- and 16-slice CT machines were matched regarding age and sex. Standard routine CT parameters were used on each CT system with helical acquisition in the posterior fossa; the parameters varied regarding collimation and radiation dose. Three blinded readers independently assessed the cases regarding image quality, infra- and supratentorial artifacts and delineation of brain parenchymal structures on a five-point ordinal scale. Reading orders were randomized. A proportional odds model that accounted for the correlated nature of the data was fit using generalized estimating equations. Posterior fossa artifacts were significantly reduced, and the delineation of infratentorial brain structures was significantly improved with the thinner collimation used for the newer CT systems (p<0.001). No significant differences were observed for midbrain structures (p>0.5). The thinner collimation available on modern CT systems leads to reduced posterior fossa artifacts and to a better delineation of brain parenchyma in the posterior fossa.

View details for DOI 10.1007/s00330-008-0937-6

View details for Web of Science ID 000257440700023

View details for PubMedID 18389247

Abstract

Non-contrast-enhanced cranial computed tomography (NECT) and CT angiography (CTA) are the most frequently used modalities in the triage of patients with acute ischemic and hemorrhagic stroke. CTA bone removal can improve the delineation of vasculature closely adjacent to bony structures, which is sometimes limited in standard CTA. The aim of this study was the evaluation of the clinical benefit of bone subtraction (BS) regarding delineation of cerebral vasculature, reading time and depiction of vascular pathologies compared to standard CTA without BS. A total of 100 patients who underwent NECT and supraaortic CTA on a 64-slice CT system were retrospectively included in the study. Bone removal was performed by subtraction of the NECT data from the CTA data using a dedicated workstation. Standard and BS CTA of each patient was reviewed for delineation of cerebral vasculature (grading scale from 1 = "excellent delineation" to 10 = "hardly any delineation"), reading time and depiction of vascular pathologies (standardized catalog) by two blinded readers. For BS data sets, the quality of BS was rated by a combination of the criteria complete bone removal, depiction of vascular structures and sufficient quality for diagnostic evaluation. The use of BS significantly reduced reading time from 4.60 min to 3.49 min (p<0.001). Performing BS, the quality of vascular delineation of the cerebral arteries, cerebral veins and cavernous segment of the ICA increased significantly as compared to standard CTA (1.70 vs. 2.70; 2.60 vs. 4.12; 2.35 vs. 4.40, all p<0.001). Consensus reading showed 41 pathologies in 35 patients. Diagnosis was missed or wrong overall in 15 cases, with 3 missed aneurysms (CTA: 2 vs. BS: 1), 8 wrong stenotic findings (CTA: 3 vs. BS: 5) and 4 missed partial thromboses (CTA: 2 vs. BS: 2). Performing BS in supraaortic CTA for the evaluation of cerebral vasculature reduces reading time and improves delineation of vessels. Diagnostic accuracy in general is not improved by BS, as the diagnostic accuracy of stenotic vessel alterations is reduced by potential truncation artifacts, but the detection rate of cerebral aneurysms slightly increases.

View details for DOI 10.1007/s00330-008-0855-7

View details for Web of Science ID 000254848400016

View details for PubMedID 18224325

Abstract

The aim of the present study was to characterize coronary plaques by Multi-Slice Computed Tomography (Siemens sensation 16, Forcheim, Germany) before significant angiographic progression occurred and to compare them to non-progressing lesions. The MSCT-morphology of coronary plaques leading to a rapid angiographic disease progression is not yet studied. In a series of 68 patients who were scheduled for surveillance angiography 6 months later, MSCT-angiography was done shortly after the baseline catheterisation-procedure. After surveillance angiography rapid progressive lesions with an increase of the stenosis severity of >20% were identified and analysed on the baseline MSCT-scan and were compared to non-progressing lesions. Six months after coronary stenting we observed significant progression of de novo stenoses in 10/438 coronary segments. The progression of four lesions lead to angina pectoris symptoms and the remaining six lesions progressed silently. Analysis of the lesion morphology by MSCT revealed that 5/10 (50%) progressing lesions were non-calcified 3/10 (30%) were predominantly non-calcified and 2/10 (20%) were mainly calcified on the baseline MSCT-scan. In the 428 segments without disease progression atherosclerotic lesions were found in 225 segments on MSCT. Non-calcified plaques were identified in 46 (20%), predominantly non-calcified lesions in 58 (26%) and predominantly calcified lesions in 121 (54%) segments. The average number of diseased coronary segments between patients with and without lesion progression was not significantly different between progressors and non-progressors with a higher prevalence of non-calcified segments in the progressor group (1.1 vs. 0.63). Rapid progression of the angiographic stenosis severity during a 6 months period occurs most frequently in coronary segments revealing non-calcified or predominantly non-calcified plaques as determined by MSCT, whereas lesion progression is rare in predominantly calcified segments. This represents first evidence that non-calcified lesions may be involved in the process of plaque rupture.

View details for DOI 10.1007/s10554-007-9278-9

View details for Web of Science ID 000254487200009

View details for PubMedID 17990073

Abstract

Comprehensive CT angiography protocols offering a simultaneous evaluation of pulmonary embolism, coronary stenoses and aortic disease are gaining attractiveness with recent CT technology. The aim of this study was to assess the diagnostic accuracy of a specific dual-source CT protocol for chest pain assessment. One hundred nine patients suffering from acute chest pain were examined on a dual-source CT scanner with ECG gating at a temporal resolution of 83 ms using a body-weight-adapted contrast material injection regimen. The images were evaluated for the cause of chest pain, and the coronary findings were correlated to invasive coronary angiography in 29 patients (27%). The files of patients with negative CT examinations were reviewed for further diagnoses. Technical limitations were insufficient contrast opacification in six and artifacts from respiration in three patients. The most frequent diagnoses were coronary stenoses, valvular and myocardial disease, pulmonary embolism, aortic aneurysm and dissection. Overall sensitivity for the identification of the cause of chest pain was 98%. Correlation to invasive coronary angiography showed 100% sensitivity and negative predictive value for coronary stenoses. Dual-source CT offers a comprehensive, robust and fast chest pain assessment.

View details for DOI 10.1007/s00330-007-0803-y

View details for Web of Science ID 000254235900019

View details for PubMedID 18034246

Abstract

The purpose of our study was to compare the detection rate of bone manifestations of multiple myeloma in whole-body MRI compared with MDCT and to assess accuracy in staging.Forty-one patients with histologically confirmed myeloma were prospectively examined with a whole-body MDCT protocol and whole-body MRI on a 1.5-T system. The MRI protocol consisted of T1-weighted spin-echo and STIR sequences. For data analysis, the entire skeleton was divided into 61 regions per patient. Image evaluation was performed in a consensus reading by two radiologists blinded to the patients' history, with separate evaluation of each technique. The patients were staged by MRI and MDCT data separately according to the Durie and Salmon PLUS staging system.On MRI, 15 patients showed no involvement. In 26 patients, 975 regions were affected: 21 patients were stage I, two were stage II, and 18 were stage III. On MDCT, 19 patients showed no involvement. In 22 patients, 462 regions were affected. For the detection rate, MRI was statistically superior to MDCT (p < 0.001, Wilcoxon's signed rank test). According to MDCT, 25 patients were stage I, seven were stage II, and nine were stage III. In 21 patients with involvement detected on both methods, MRI showed more extensive disease than MDCT. Eleven patients were understaged with MDCT compared with MRI, which was statistically significant (p < 0.001, chi-square test).Whole-body MDCT leads to a significantly lower detection rate and staging in patients with multiple myeloma.

View details for DOI 10.2214/AJR.07.2635

View details for Web of Science ID 000254271100037

View details for PubMedID 18356461

Abstract

Cardiac magnetic resonance imaging and echocardiography are currently regarded as standard modalities for the quantification of left ventricular volumes and ejection fraction. With the recent introduction of dual-source computedtomography (DSCT), the increased temporal resolution of 83 ms should also improve the assessment of cardiac function in CT. The aim of this study was to evaluate the accuracy of DSCT in the assessment of left ventricular functional parameters with cardiac magnetic resonance imaging (MRI) as standard of reference. Fifteen patients (two female, 13 male; mean age 50.8 +/- 19.2 years) underwent CT and MRI examinations on a DSCT (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany) and a 3.0-Tesla MR scanner (Magnetom Trio; Siemens Medical Solutions), respectively. Multiphase axial CT images were analysed with a semiautomatic region growing algorithms (Syngo Circulation; Siemens Medical Solutions) by two independent blinded observers. In MRI, dynamic cine loops of short axis slices were evaluated with semiautomatic contour detection software (ARGUS; Siemens Medical Solutions) independently by two readers. End-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined for both modalities, and correlation coefficient, systematic error, limits of agreement and inter-observer variability were assessed. In DSCT, EDV and ESV were 135.8 +/- 41.9 ml and 54.9 +/- 29.6 ml, respectively, compared with 132.1 +/- 40.8 ml EDV and 57.6 +/- 27.3 ml ESV in MRI. Thus, EDV was overestimated by 3.7 ml (limits of agreement -46.1/+53.6), while ESV was underestimated by 2.6 ml (-36.6/+31.4). Mean EF was 61.6 +/- 12.4% in DSCT and 57.9 +/- 9.0% in MRI, resulting in an overestimation of EF by 3.8% with limits of agreement at -14.7 and +22.2%. Rank correlation rho values were 0.81 for EDV (P = 0.0024), 0.79 for ESV (P = 0.0031) and 0.64 for EF (P = 0.0168). The kappa value of inter-observer variability were amounted to 0.85 for EDV, ESV and EF. DSCT offers the possibility to quantify left ventricular function from coronary CT angiography datasets with sufficient diagnostic accuracy, adding to the value of the modality in a comprehensive cardiac assessment. The observed differences in the measured values may be due to different post-processing methods and physiological reactions to contrast material injection without beta-blocker medication.

View details for DOI 10.1007/s00330-007-0767-y

View details for Web of Science ID 000253006700016

View details for PubMedID 17909817

Abstract

The purpose of this study is to assess the accuracy of dual energy CT (DECT) in the characterization of renal and ureteral stones.Twenty-four renal calculi of known variable composition were scanned on a dual-source CT scanner (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany) in dual energy (DECT) mode. Scan parameters for DECT were: tube potentials, 80 and 140 kV; tube current, 342 and 76 mA.s; collimation, 14 x 1.2 mm2. Dual energy properties of calculi were used to differentiate between uric acid (UA) and other calculi. Differentiation was based on a 3-material decomposition implemented in the dual energy software (Syngo VA 11; Siemens Medical Solutions). Color coding was used to display different types of stones and their DECT properties were characterized with density measurements at both photon energies. Subsequently, 20 consecutive patients with known or suspected uroliths were scanned using identical scan parameters. Stone size and material were assessed in DECT and compared with the chemical analyses of stones after mechanical extraction.With DECT characterization, differentiation of UA from other calculi was possible. Additionally, differentiation between cystine and struvite stones was shown to be feasible in vitro. In the patient cohort, DECT correctly characterized 4 UA calculi, 4 mixed, multiple calcified, and 1 cystine stone. The calculi were displayed in specific colors, ie, UA stones in red and calcified stones in blue.With dual energy CT techniques, the UA, cystine, struvite, and mixed renal calculi can be differentiated from other types of stones in vitro and in vivo. This is of clinical relevance as UA uroliths may be treated pharmacologically rather than with surgical extraction or extracorporal shockwave lithotripsy.

View details for Web of Science ID 000252569300004

View details for PubMedID 18197063

Abstract

Assessment of the clinical benefit of i.v. contrast enhanced diagnostic CT (CE-CT) compared to low dose CT with 20 mAs (LD-CT) without contrast medium in combined [(18)F]-FDG PET/CT examinations in restaging of patients with lymphoma.45 patients with non-Hodgkin lymphoma (n=35) and Hodgkin's disease (n=10) were included into this study. PET, LD-CT and CE-CT were analyzed separately as well as side-by-side. Lymphoma involvement was evaluated separately for seven regions. Indeterminate diagnoses were accepted whenever there was a discrepancy between PET and CT findings. Results for combined reading were calculated by rating indeterminate diagnoses according the suggestions of either CT or PET. Each patient had a clinical follow-up evaluation for >6 months.Region-based evaluation suggested a sensitivity/specificity of 66/93% for LD-CT, 87%/91% for CE-CT, 95%/96% for PET, 94%/99% for PET/LD-CT and 96%/99% for PET/CE-CT. The data for PET/CT were obtained by rating indeterminate results according to the suggestions of PET, which turned out to be superior to CT. Lymphoma staging was changed in two patients using PET/CE-CT as compared to PET/LD-CT.Overall, there was no significant difference between PET/LD-CT and PET/CE-CT. However, PET/CE-CT yielded a more precise lesion delineation than PET/LD-CT. This was due to the improved image quality of CE-CT and might lead to a more accurate investigation of lymphoma.

View details for DOI 10.3413/nukmed-0114

View details for Web of Science ID 000253638400009

View details for PubMedID 18278211

Abstract

Reliable risk stratification is crucial for efficient prevention of coronary artery disease. The following prospective study determined the predictive value of coronary calcifications for future cardiovascular events.We included 1726 asymptomatic individuals (1018 men, 708 women, age 57.7 +/- 13.3 years) referred for a cardiological examination. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomography scanner. For quantification of coronary calcifications, we calculated the Agatston score. Over a mean observation period of 40.3 +/- 7.3 months we registered the event rate for cardiac death (CD) and myocardial infarction (MI).The Agatston score in patients who died of CD (n = 65) or had an MI (n = 114) was significantly higher compared with those without cardiac events (458 +/- 228 vs 206 +/- 201, P < .01). An Agatston score above the 75th percentile was associated with a significantly higher annualized event rate for MI (3.6% vs 1.6%, P < .05) and for CD (2.2% vs 0.9%) compared with patients with scores below the 75th percentile. No cardiac events were observed in patients where coronary calcifications could be excluded.By determination of coronary calcifications, patients at risk for future MI and CD could be identified within an asymptomatic population independent of concomitant risk factors. At the same time, future cardiovascular events could be excluded in patients without coronary calcifications.

View details for DOI 10.1016/j.ahj.2007.08.024

View details for Web of Science ID 000251732400024

View details for PubMedID 18082507

Abstract

Our aim was to evaluate the correlation of test bolus (TB) curve parameters with main bolus (MB) contrast density for cardiac 16-slice computed tomography, and to correlate observed enhancement with patient body weight.Sixty patients with known or suspected coronary artery disease were included in a prospective double-blind study. Contrast material containing 300 mg iodine/mL (Iomeprol 300; Imeron 300, Bracco Imaging SpA, Milan, Italy) and 400 mg iodine/mL (Iomeprol 400; Imeron 400) was injected at a rate of 1 g of iodine/second. Contrast densities (Hounsfield units) of the MB were determined in the left cardiac system. The peak density (PD) of maximum attenuation and the area under the curve (AUC) of the TB curve were calculated for each patient. The dependency of MB contrast attenuation on these parameters and on patient body weight was evaluated.Positive correlations (r = 0.52 and r = 0.56, respectively; P < .0001) were obtained between the PD and AUC of the TB curve with the mean density of the MB. Stronger correlations (r = 0.63 and r = 0.64, respectively; P < .0001) between PD and AUC of the TB curve and MB attenuation were found when patient body weight was included in the analysis.Strong correlation of the PD and AUC of the TB curve with the mean density of the MB is observed when patient body weight is considered. Contrast injection protocols may be optimized, and variations of MB contrast density in the left ventricle and main coronary arteries reduced, by taking these TB parameters and the weight of the patient into account.

View details for DOI 10.1016/j.acra.2007.08.005

View details for Web of Science ID 000251984600006

View details for PubMedID 18078906

Abstract

A retrospective analysis of a case series was performed.To give recommendations for the prevention and operative treatment of thoracic and thoracoabdominal aortic lesions in association with spinal interventions.Aortic lesions after spinal interventions for traumatic vertebral fractures, segmental spondylodiscitis, or vertebral metastasis are fortunately rare, but associated with a high perioperative mortality rate and absolute numbers are unknown. Therefore, preventive strategies to avoid perioperative major vessel injuries and recommendations for the operative treatment of aortic lesions related to spinal surgery are required.The clinical course of 10 patients with an acute aortic hemorrhage or an increased intraoperative risk for aortic injuries in association with primary or secondary spinal interventions is reported. All patients were evaluated before surgery by orthopedic trauma surgeons, vascular surgeons, and diagnostic radiologists.Five patients had preventive vascular interventions to avoid major aortic injuries during spinal reinterventions, and 5 patients were treated as an emergency for acute intraoperative hemorrhage related to spinal interventions. The operative treatment was performed by direct aortic sutures (n = 3), segmental alloplastic reconstructions (n = 2), or endovascular stent graft implantations (n = 3). Prophylactic banding of the thoracic aorta during thoracotomy or a femoral access for possible aortic balloon blockade was performed in patients with an estimated lower risk for an aortic laceration caused by malpositioned pedicle screws. No perioperative mortality was observed in patients treated by this interdisciplinary concept, but 1 patient treated under emergency condition for spondylodiscitis with an initially unrecognized aortic lesion died.In patients with complex spinal trauma, spondylodiscitis or difficult vertebral reinterventions, and an increased risk of major vessel injury, a preoperative interdisciplinary evaluation is recommended, even under emergency conditions. Endovascular stent graft technique is an additional option for prevention and treatment of suspected or acute aortic injuries of thoracic and infrarenal aortic lesions, whereas injuries to the visceral aortic segment still require advanced vascular reconstructions.

View details for Web of Science ID 000251442600032

View details for PubMedID 18245991

Abstract

Coronary catheter angiography is considered to be the standard of reference for the diagnosis of coronary artery disease (CAD) and the grading of coronary artery stenoses. Even with the established generation of 16- and 64-multislice CT (MSCT) systems, with remarkable results reported for diagnostic accuracy, a substantial number of limitations remain, hindering full acceptance of the method as a standard technique in the clinical cascade for CAD patients. Recently, dual-source CT (DSCT) with improved temporal resolution has been introduced into clinical routine, raising the hope that some of the earlier problems might be overcome. MSCTA with 64-slice CT scanners has successfully been validated for the evaluation of clinically relevant lumen reduction of the coronary arteries with high negative predictive values and for the simultaneous assessment of pulmonary embolism, coronary artery stenoses, and aortic dissection and aneurysm in patients with chest pain ("triple rule out"). However, certain limitations continue to exist including partial volume effects due to heavy calcium deposits in the coronary artery wall, impaired assessability of coronary artery branches smaller than 2 mm in diameter, and impaired assessability of patients with a high heart rate and/or arrhythmia. While MSCT has mainly been tested to detect obstructive CAD, an accurate assessment of regional and global ventricular function, as well as of the aortic and mitral valves, might be feasible using DSCT, since image reconstruction is possible in virtually any phase of the cardiac cycle with a sufficiently high temporal resolution. DSCT is a robust method for the evaluation of patients with higher heart rates and arrhythmias and, in most cases, obviates the need for beta-blocker premedication. While the evaluation of coronary artery stenoses will remain the primary clinical indication for cardiac DSCT, a simultaneous and sufficiently accurate assessment of global left ventricular functional parameters, regional wall motion, and valve assessment becomes feasible with a single scan.

View details for PubMedID 18376453

Abstract

Myxomas of the left atrial cavity of the heart are a rare occurrence. Incidental diagnosis is mostly based on transthoracic echocardiography. Contrast enhanced ultrasound (CEUS) seems to be a promising new diagnostic option for diagnosis and preoperative planning of treatment for patients with myxoma. It is an additional examination to baseline ultrasound and CT or MRT.We report a case of a 63-year-old woman with myxoma of the left atrial cavity of the heart in which CEUS helped to define the location and its relation to the heart valve.In contrast enhanced ultrasound (CEUS), the oval mass in the left atrium was scanned in the 4-chamber view. Perfusion of the mass was examined by visualising gradual contrast enhancement. An involvement of the mitral valve could be excluded. The tumour base could be clearly depicted and differentiated from normal surrounding tissue. No thrombotic material was found in the left atrium (LA) or ventricle (LV).CEUS could detect the mass and offer additional information such as vascularity, mobility, attachment to the valve and possible thrombi. Dual Source CT (DSCT) confirmed the findings and provided a very clear morphological characterisation and dynamic evaluation of mobility and valve interference.

View details for DOI 10.1055/s-2007-963046

View details for Web of Science ID 000252360800011

View details for PubMedID 17492576

Abstract

The aim of this study was to evaluate the diagnostic accuracy of dual-source computed tomography (DSCT) with reference to invasive coronary angiography in the diagnosis of coronary artery disease (CAD) on a per-patient as well as on a per-segment basis.Thirty-five patients with known or suspected CAD underwent both DSCT (Somatom Definition, Siemens Medical Solutions) and quantitative x-ray coronary angiography (QCA). Parameters of CT acquisition were gantry rotation time 0.330 seconds (ie, temporal resolution 83 milliseconds), tube voltage 120 kV, tube current 560 mA with ECG-triggered tube current modulation and full current at 70% of the cardiac cycle for heart rates below 70 beats per minute or full current between 30% and 80% for higher and arrhythmic heart rates. The pitch was also adapted to the heart rate, ranging from 0.2 to 0.43. Volume and flow rate of contrast material (Ultravist 370, Schering AG) were adapted to the patient's body weight. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DSCT in the detection or exclusion of significant CAD (ie, stenoses >50%) were evaluated on a per-patient and per-segment basis.All 35 CT angiograms were of diagnostic image quality. QCA demonstrated significant CAD in 48% (n = 17) and nonsignificant disease or normal coronary angiograms in 52% (n = 18) of the patients. Sensitivity, specificity, PPV, and NPV of DSCT on a per-patient basis were 100%, 89%, 89%, and 100%, respectively. On a per-segment basis, 473 of 481 coronary artery segments were assessable (98%). QCA demonstrated stenoses >50% in 32 segments (7%), and no disease or nonsignificant disease in 433 segments (93%). For the detection of stenoses >50% on a per-segment basis, DSCT showed a sensitivity, specificity, PPV, and NPV of 88%, 98%, 78%, and 99%, respectively.The comparison of coronary DSCT with QCA shows a very robust image quality and a high diagnostic accuracy in a patient-based as well as a per-segment analysis. Maximal sensitivity and NPV in the per-patient analysis show the strength of the technique in ruling out significant CAD.

View details for Web of Science ID 000249718800004

View details for PubMedID 17984765

Abstract

The aim of the present study was to assess the clinical performance of a dual X-ray source multi-slice CT (MSCT) with high temporal resolution to assess the coronary status in patients with an intermediate pretest likelihood for significant coronary artery disease (CAD) without using negative chronotropic pretreatment.Dual-source CT (DSCT) angiography (Siemens Definition) was performed in 90 patients with an intermediate likelihood for CAD who were referred for invasive coronary angiography. DSCT generated data sets with diagnostic image quality in 88 of the overall 90 patients. In six of seven patients with atrial fibrillation and in 46 of 48 patients with heart rates (HR)>65 b.p.m. image quality was diagnostic. In 20 of 21 patients with at least one stenosis>50% (sensitivity 95%) were correctly identified by DSCT-angiography. In 60 of 67 patients, a lesion>50% was correctly excluded (specificity 90%; positive predictive value 74%). The accuracy to detect patients with coronary stenoses>50% (sensitivity 92 vs. 100%; specificity 88 vs. 91%) was not significantly different among patients with HR>65 b.p.m. (n=46) and <65 b.p.m. The concordance of DSCT-derived stenosis quantification showed good correlation (r=0.76; P<0.001) to quantitative coronary angiography with a slight trend to overestimate the stenosis degree.DSCT is a non-invasive tool that allows to accurately rule out coronary stenoses in patients with an intermediate pretest likelihood for CAD, independent of the HR.

View details for DOI 10.1093/eurheartj/ehm294

View details for Web of Science ID 000250515100015

View details for PubMedID 17644815

Abstract

Computer-aided detection (CAD) algorithms help to detect colonic polyps at CT colonography (CTC). The purpose of this study was to evaluate the accuracy of CAD versus an expert reader in CTC. One hundred forty individuals (67 men, 73 women; mean age, 59 years) underwent screening 64-MDCT colonography after full cathartic bowel cleansing without fecal tagging. One expert reader interpreted supine and prone scans using a 3D workstation with integrated CAD used as "second reader." The system's sensitivity for the detection of polyps, the number of false-positive findings, and its running time were evaluated. Polyps were classified as small (< or =5 mm), medium (6-9 mm), and large (> or =10 mm). A total of 118 polyps (small, 85; medium, 19; large, 14) were found in 56 patients. CAD detected 72 polyps (61%) with an average of 2.2 false-positives. Sensitivity was 51% (43/85) for small, 90% (17/19) for medium, and 86% (12/14) for large polyps. For all polyps, per-patient sensitivity was 89% (50/56) for the radiologist and 73% (41/56) for CAD. For large and medium polyps, per-patient sensitivity was 100% for the radiologist, and 96% for CAD. In conclusion, CAD shows high sensitivity in the detection of clinically significant polyps with acceptable false-positive rates.

View details for DOI 10.1007/s00330-007-0579-0

View details for Web of Science ID 000249522900019

View details for PubMedID 17429646

Abstract

Appropriate diagnosis and therapy of coronary artery disease (CAD) frequently require information about both the functional and morphological status of the coronary artery tree. We hypothesized that the combination of multislice spiral CT (MDCT) angiography and myocardial perfusion SPECT (MPI) provides accurate allocation of perfusion defects (PD) to their determining coronary lesion.Twenty patients (14 male, mean age 64+/-9.2 years) with known CAD were retrospectively studied. Gated MPI, CT angiography using a 16-detector CT scanner, and conventional coronary angiography (CCA) were performed in each patient. Reversible and fixed PD were subsequently allocated to their determining lesion separately by different observers for MDCT angiography and CCA.All patients showed significant CAD in CCA; six patients with one-, six with two-, six with three-, and two with four-vessel disease; three patients had bypass grafts; and five patients had prior myocardial infarction. Correct diagnosis of CAD was stated in 14 of 20 patients by MDCT angiography. Five reversible and five fixed PD were detected in 9 of 20 patients; one patient showed both reversible and fixed PD. Five of five reversible PD could be allocated to appropriate coronary artery stenoses in CCA. In MDCT angiography, five of five reversible PD were allocated to the same lesions; all lesions were rated as >/=50%.The preliminary results of the present study show high accuracy for multislice spiral CT angiography to allocate reversible perfusion defects in myocardial scintigraphy to their determining coronary artery lesions in a small patient collective with known coronary artery disease.

View details for DOI 10.1016/j.clinimag.2007.03.013

View details for Web of Science ID 000249573400003

View details for PubMedID 17825738

Abstract

The purpose of this study is to investigate the diagnostic potential of color-coded Doppler sonography (CCDS), power-Doppler (PD) and B-flow ultrasound in assessing the degree of extracranial internal carotid artery (ICA) stenosis in comparison to CT-angiography (MD-CTA). Thirty-two consecutive patients referred for CTA with 41 ICA-stenoses were included in this prospective study. MD-CTA was performed using a 64 row scanner with a CTDIvol of 13.1 mGy/cm. In CTA, CCDS, PD and B-flow, the degree of stenosis was evaluated by the minimal intrastenotic diameter in comparison to the poststenotic diameter. Two radiologists performed a quantitative evaluation of the stenoses in consensus blinded to the results of ultrasound. These were correlated to CTA, CCDS, PD and B-flow, intraoperative findings and clinical follow-up. Grading of the stenoses in B-flow ultrasound outperformed the other techniques in terms of accuracy with a correlation coefficient to CTA of 0.88, while PD and CCDS measurements yield coefficients of 0.74 and 0.70. Bland-Altman analysis additionally shows a very little bias of the three US methods between 0.5 and 3.2 %. There is excellent correlation (coefficient 0.88, CI 0.77-0.93) with 64-MD-CTA and B-flow ultrasound in terms of accuracy for intrastenotic and poststenotic diameter. Duplex sonography is useful for screening purposes.

View details for DOI 10.1007/s00330-006-0488-7

View details for Web of Science ID 000247969800027

View details for PubMedID 17119974

View details for DOI 10.1002/art.22803

View details for Web of Science ID 000248629900042

View details for PubMedID 17665437

Abstract

The value of combined positron emission tomography (PET)/computed tomography (CT) in the follow-up of patients with breast cancer with elevated tumor markers but without proven metastases or local recurrence was assessed.Thirty-four women underwent PET/CT. The PET and CT images were first analyzed separately; fused findings were then interpreted, blinded to the results of the other modalities. The results of CT, PET, and PET/CT were compared with each other and correlated to the final diagnosis.The PET/CT identified 149 malignant foci in 24 patients (71%). The CT detected 96 of these foci in 18 patients, whereas PET identified 124 foci in 17 patients. Differences between CT and PET were not significant. Differences between PET/CT and CT (P < 0.01) and PET/CT and PET (P < 0.01) were significant. The person-based sensitivity of PET/CT, PET, and CT was 96%, 88% and 96%, respectively. Specificity of PET/CT, PET, and CT was 89%, 78%, and 78%, respectively.The PET/CT is a valuable modality for the follow-up of patients with breast cancer and elevated levels of tumor markers.

View details for Web of Science ID 000248551400025

View details for PubMedID 17882045

Abstract

An 89-year-old female presented with typical symptoms of acute diverticulitis. Abdominal CT revealed an abdominal wall hernia with signs of acute incarceration in the lateral part of the transverse abdominis muscle and rupture of the transversalis fascia. The findings were confirmed intraoperatively. The present case underlines the diagnostic importance of abdominal CT, especially in patients with acute abdomen, allowing for selection of appropriate therapy options.

View details for Web of Science ID 000248005600007

View details for PubMedID 17666318

Abstract

Multislice computed tomography (MSCT) has started to replace Electron beam CT for quantitation of coronary artery calcium. However no study has evaluated the diagnostic accuracy of MSCT for prediction of coronary artery disease (CAD) in a symptomatic patient population using the volume score.1347 symptomatic subjects (male = 803, mean age = 62 years) with suspected CAD underwent MSCT studies 1 +/- 2 days before the coronary angiogram. The Agatston (ACS) and Volumetric calcium score (VCS) were calculated using a proprietary workstation. Statistical analyses included the Pearson's correlation coefficient and the nonparametric Mann-Whitney U-test to compare the calcium score in different age groups and between men and women. Sensitivity, specificity and predictive accuracy were calculated for different calcium thresholds for prediction of CAD. ROC curve analyses were used to establish relations between the coronary calcium score and presence or absence of CAD. In 720 (53%) subjects (male = 419) angiography revealed a minimal lumen diameter stenosis greater than 50%. Patients with significant CAD had significantly higher total calcium score values than patients without CAD (P = 0.001). ACS and VCS demonstrate a close correlation for the whole study group, r = 0.99. The overall sensitivity of any calcium to predict stenosis was 99%, specificity = 32%. Exclusion of calcium was highly accurate for exclusion of CAD in subjects older than 50 years (predictive accuracy = 98%). An absolute cutoff >100 and an age and sex specific threshold (score over 75th percentile) were identified as the cutoff levels with the highest sensitivities (86-89%) and lowest false positive rates (20-22%). ROC analyses revealed MSCT calcium scanning as a good clinical test which can be performed with similar accuracy in all age groups with an area under the curve of 0.84.Determination of coronary calcium with MSCT is an accurate imaging modality for prediction of significant CAD in a patient population with intermediate likelihood of CAD. Exclusion of any calcium provided strong evidence that patients older than 50 years did not have obstructive CAD. ACS and VCS show an equivalent diagnostic accuracy.

View details for DOI 10.1007/s10554-006-9189-1

View details for Web of Science ID 000246392600010

View details for PubMedID 17160425

Abstract

The aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOM Definition Dual Source CT (DSCT; Siemens, Forchheim, Germany) system in dual energy mode at tube voltages of 140 and 80 kVp and a ratio of 1:3 between tube currents. Weighted CT Dose Index ranged between 7 and 8 mGy, remaining markedly below reference dose values for the respective body regions. Image post-processing with three-material decomposition was applied to differentiate iodine or collagen from other tissue. The results showed that a differentiation and depiction of contrast material distribution is possible in the brain, the lung, the liver and the kidneys with or without the underlying tissue of the organ. In angiographies, bone structures can be removed from the dataset to ease the evaluation of the vessels. The differentiation of collagen makes it possible to depict tendons and ligaments. Dual energy CT offers a more specific tissue characterization in CT and can improve the assessment of vascular disease. Further studies are required to draw conclusions on the diagnostic value of the individual applications.

View details for DOI 10.1007/s00330-006-0517-6

View details for Web of Science ID 000246385000014

View details for PubMedID 17151859

Abstract

The aim of this study was to assess the performance of a software tool for quantitative coronary artery analysis of computed tomography coronary angiography (CT-QCA) in comparison with invasive coronary angiography with quantitative analysis (CAG-QCA) as standard of reference. Two radiologists reviewed the CT angiography data sets (Siemens Sensation 64) of 25 patients, grading coronary artery stenoses visually and with a software tool (Circulation, Siemens). Twenty-three data sets with sufficient image quality were included in the final analysis. CAG revealed a total of 30 wall irregularities and 28 stenoses, of which 17 were graded as moderate and nine as hemodynamically significant. CT-QCA showed a better agreement to CAG-QCA, with a systematic overestimation of the degree of stenosis of 6.1% and limits of agreement of +36.1% and -23.9; the correlation coefficient was 0.82 (p < 0.0001). Using CT-QCA, sensitivity, specificity, and positive and negative predictive value were 89%, 100%, 89%, and 100%, respectively, for significant area stenoses greater than 75%. The positive predictive value for the visual assessment amounted to 53%. Interobserver variability between CT-QCA and visual assessment showed a kappa value of 0.72. In conclusion, software-supported CT-QCA makes it possible to quantify significant coronary artery stenoses automatically, with good agreement to CAG-QCA.

View details for DOI 10.1007/s00330-006-0512-y

View details for Web of Science ID 000246385000007

View details for PubMedID 17180326

Abstract

To evaluate the performance of a prototype computer-aided diagnosis (CAD) tool using artificial intelligence techniques for the detection of pulmonary embolism (PE) and the possible benefit for general radiologists.Forty multidetector row computed tomography datasets (16/64- channel scanner) using 100 kVp, 100 mAs effective/slice, and 1-mm axial reformats in a low-frequency reconstruction kernel were evaluated. A total of 80 mL iodinated contrast material was injected at a flow rate of 5 mL/seconds. Primarily, six general radiologists marked any PE using a commercially available lung evaluation software with simultaneous, automatic processing by CAD in the background. An expert panel consisting of two chest radiologists analyzed all PE marks from the readers and CAD, also searching for additional finding primarily missed by both, forming the ground truth.The ground truth consisted of 212 emboli. Of these, 65 (31%) were centrally and 147 (69%) were peripherally located. The readers detected 157/212 emboli (74%) leading to a sensitivity of 97% (63/65) for central and 70% (103/147) for peripheral emboli with 9 false-positive findings. CAD detected 168/212 emboli (79%), reaching a sensitivity of 74% for central (48/65) and 82%(120/147) for peripheral emboli. A total of 154 CAD candidates were considered as false positives, yielding an average of 3.85 false positives/case.The CAD software showed a sensitivity comparable to that of the general radiologists, but with more false positives. CAD detection of findings incremental to the radiologists suggests benefit when used as a second reader. Future versions of CAD have the potential to further increase clinical benefit by improving sensitivity and reducing false marks.

View details for DOI 10.1016/j.acra.2007.02.007

View details for Web of Science ID 000246861300003

View details for PubMedID 17502254

Abstract

The diagnostic accuracy of screening for bone metastases was evaluated using whole-body magnetic resonance imaging (WB-MRI) compared with combined fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (FDG-PET-CT). In a prospective, blinded study, 30 consecutive patients (18 female, 12 male; 24-76 years) with different oncological diseases and suspected skeletal metastases underwent FDG-PET-CT as well as WB-MRI with the use of parallel imaging (PAT). With a 32-channel scanner, coronal imaging of the entire body and sagittal imaging of the complete spine was performed using T1-weighted and short tau inversion recovery (STIR) sequences in combination. PET-CT was conducted using a low-dose CT for attenuation correction, a PET-emission scan and diagnostic contrast-enhanced CT scan covering the thorax, abdomen and pelvis. Two radiologists read the MRI scans, another radiologist in combination with a nuclear medicine physician read the PET-CT scans, each in consensus. The standard of reference was constituted by radiological follow-up within at least 6 months. In 28 patients, 102 malignant and 25 benign bone lesions were detected and confirmed. WB-MRI showed a sensitivity of 94% (96/102), PET-CT exams achieved 78% (79/102; P<0.001). Specificities were 76% (19/25) for WB-MRI and 80% (20/25) for PET-CT (P>0.05). Diagnostic accuracy was 91% (115/127) and 78% (99/127; P<0.001), respectively. Cut-off size for the detection of malignant bone lesions was 2 mm for WB-MRI and 5 mm for PET-CT. WB-MRI revealed ten additional bone metastases due to the larger field of view. In conclusion, WB-MRI and FDG-PET-CT are robust imaging modalities for a systemic screening for metastatic bone disease. PAT allows WB-MRI bone marrow screening at high spatial resolution and with a diagnostic accuracy superior to PET-CT.

View details for DOI 10.1007/s00330-006-0361-8

View details for Web of Science ID 000244753900009

View details for PubMedID 16951929

Abstract

Electrocardiogram-gated computed tomographic angiography is increasingly used in the differential diagnosis of acute chest pain. We studied the optimal timing of contrast material injection using a test bolus and a bolus-tracking technique.Thirty patients were prospectively included in the study. Volume and flow of high concentration contrast material were adapted to body weight. The scan delay was determined using either a test bolus or a bolus-tracking technique. Attenuation profiles of the different vascular districts were measured to evaluate the timing techniques.In all the patients except for one, an adequate and homogeneous contrast enhancement of more than 200 Hounsfield units (HU) was achieved (285 +/- 45 HU) in the different vascular districts. The pulmonary transit time in the test bolus group was 7 seconds (range, 4-11 seconds). Differences and variability of pulmonary and aortic enhancement were small in both groups (13 +/- 48 HU vs -9 +/- 21 HU), with differences of less than 70 HU over the craniocaudal range and very small intraindividual differences between pulmonary attenuation and systemic attenuation.Contrast administration regimens for electrocardiogramgated computed tomographic angiography of the chest can be optimized using the bolus-tracking method in the ascending aorta, with a short delay after trigger. Body weight adaptation of volume and injection rate of the contrast material results in a reliable simultaneous opacification of the pulmonary and systemic vasculature.

View details for Web of Science ID 000245456700019

View details for PubMedID 17414765

Abstract

The prophylactic effect of postmenopausal hormone replacement therapy on coronary atherosclerosis remains controversial. We, therefore, examined the influence of combined estrogen/progestin therapy on the progression of coronary calcium as a marker of coronary atherosclerosis. We determined the extent of coronary calcium in 277 women (age 57 +/- 6 years, time after menopause 3.9 +/- 2.4 years, group I) at the beginning of hormone replacement therapy using multislice computed tomography. For quantification, we calculated the volume score. After an observation period of 3 years, we determined the progression of coronary calcium in a second scan. The results were compared with those from an age- and risk factor-adjusted group of postmenopausal women without hormone substitution (group II). No significant difference was found in the volume score (59 +/- 95 vs 58 +/- 88) or risk factor distribution between the 2 groups on study entry. In 56 women of group I and 52 women of group II, coronary calcium could be excluded on the initial scan (p = NS). After a mean observation time of 38.5 +/- 4.9 months, we observed no significant difference between the 2 groups regarding an increase in volume score (17 +/- 24 vs 19 +/- 27, p = NS) or the fraction of women with an increase in volume score (82.2% vs 84.2%). In conclusion, a reduced progression of coronary calcium in postmenopausal women on combined estrogen/progestin therapy could not be observed compared with a matched group of women without hormone substitution.

View details for DOI 10.1016/j.amjcard.2006.08.040

View details for Web of Science ID 000243947900017

View details for PubMedID 17261401

Abstract

The value and limitations of (11)C-choline PET and PET/CT for the detection of prostate cancer remain controversial. The aim of this study was to investigate the diagnostic efficacy of (11)C-choline PET and PET/CT in a large group of patients with suspected prostate cancer.Fifty-eight patients with clinical suspicion of prostate cancer underwent (11)C-choline PET (25/58, Siemens ECAT Exact HR+) or PET/CT (33/58, Philips Gemini) scanning. On average, 500 MBq of (11)C-choline was administered intravenously. Studies were interpreted by raters blinded to clinical information and other diagnostic procedures. Qualitative image analysis as well as semiquantitative SUV measurement was carried out. The reference standard was histopathological examination of resection specimens or biopsy.Prevalence of prostate cancer in this selected patient population was 63.8% (37/58). (11)C-choline PET and PET/CT showed a sensitivity of 86.5% (32/37) and a specificity of 61.9% (13/21) in the detection of the primary malignancy. With regard to metastatic spread, PET showed a per-patient sensitivity of 81.8% (9/11) and produced no false positive findings.Based on our findings, differentiation between benign prostatic changes, such as benign prostatic hyperplasia or prostatitis, and prostate cancer is feasible in the majority of cases when image interpretation is primarily based on qualitative characteristics. SUV(max) may serve as guidance. False positive findings may occur due to an overlap of (11)C-choline uptake between benign and malignant processes. By providing functional information regarding both the primary malignancy and its metastases, (11)C-choline PET may prove to be a useful method for staging prostate cancer.

View details for DOI 10.1007/s00259-006-0190-7

View details for Web of Science ID 000242504400007

View details for PubMedID 16932935

Abstract

The most important differential diagnoses of acute chest pain include myocardial infarction, aortic dissection, and pulmonary embolism. The purpose of this study was to evaluate the diagnostic value of an ECG-gated 64-MDCT angiography protocol for simultaneous assessment of the pulmonary arteries, coronary arteries, and aorta within a single breath-hold.In 55 patients with acute chest pain, ECG-gated CT angiography was performed with a CT system in which 64 slices per gantry rotation were acquired. Density measurement and visual assessment of motion artifacts were performed to evaluate image quality. CT findings were correlated with results of laboratory tests and clinical follow-up. For 20 patients, two independent blinded reviewers compared findings on CT angiography with those on X-ray coronary angiography.Adequate contrast enhancement of the pulmonary vessels, coronary arteries, and aorta was achieved in all cases. Regarding image quality of the coronary arteries, there was minor blurring in seven patients, and in one examination the images did not provide enough information for diagnosis. The average image quality rating was 1.2 on a scale in which 1 indicated no artifacts; 2, minor motion artifacts; and 3, image insufficient for diagnosis. The cause of chest pain was correctly identified with MDCT in 37 patients. The diagnoses included pulmonary embolism (n = 10), coronary stenosis (n = 9), and aortic dissection (n = 1). In four patients, additional diagnoses were found with other examinations.With current techniques, ECG-gated CT angiography of the entire chest has very good image quality. The protocol proved helpful in the differential diagnosis of acute chest pain.

View details for DOI 10.2214/AJR.05.1153

View details for Web of Science ID 000245647900014

View details for PubMedID 17179348

Abstract

The aim of this study was to evaluate spiral multidetector computed tomography (MDCT) angiography using 64-slice technique in the detection of functionally relevant coronary artery stenoses (CAS).Thirty-eight patients (62+/-11 years, 28 men) with stable angina (26 with suspected and 12 with known coronary artery disease) were investigated using 64-slice MDCT angiography and gated myocardial perfusion SPECT (gated SPECT); a subgroup of 30 patients had additional invasive coronary angiography (ICA). Stenoses with luminal narrowing of >or=50% were defined as "significant" in MDCT angiography and ICA. MDCT angiography was compared with gated SPECT and the combination of gated SPECT plus ICA with respect to the detection of functionally relevant CAS.The sensitivity, specificity and negative and positive predictive values of MDCT angiography in detecting reversible perfusion defects on gated SPECT were 63%, 80%, 94% and 32%, respectively, in vessel-based analysis and 71%, 62%, 72% and 60%, respectively, in patient-based analysis. If only reversible perfusion defects on gated SPECT with CAS >or=50% on ICA were considered, the sensitivity, specificity and negative and positive predictive values were, respectively, 85%, 79%, 98% and 33% for vessel-based analysis and 85%, 59%, 83% and 61% for patient-based analysis.Sixty-four slice MDCT angiography failed to predict the functional relevance of CAS, but had a high negative predictive value in the exclusion of functionally relevant CAS in symptomatic patients.

View details for DOI 10.1007/s00259-006-0207-2

View details for Web of Science ID 000242504400002

View details for PubMedID 16951954

Abstract

Restenosis remains a major limitation of coronary catheter-based stent placement. Therefore, a reliable noninvasive diagnostic method for the evaluation of stented coronary arteries would be highly desirable. Our aim was to evaluate the diagnostic accuracy of high-resolution 64-slice computed tomography (64SCT) in a pilot study for the assessment of the lumen of coronary artery stents.Twenty-five patients underwent 64SCT of the coronary arteries and quantitative x-ray coronary angiography (QCA) after coronary artery stent placement. 64SCT coronary angiography was performed with the following parameters: spatial resolution = 0.4 x 0.4 x 0.4 mm; temporal resolution = 83-165 milliseconds; contrast agent = 80 mL at a flow rate of 5 mL/second; retrospective electrocardiogram gating. The 64SCT scans were evaluated for image quality and for the presence of significant in-stent and peri-stent (proximal and distal) stenoses. Determinations were made of the sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values (PPV and NPV) of 64SCT for the detection or exclusion of stenoses.A total of 46 stents were evaluated, of which 45 (98%) were of diagnostic image quality. Significant in-stent restenosis or occlusion was detected on QCA in 8/45 cases (>/=50% stenosis = 6; occlusion = 2). The sensitivity, specificity, accuracy, PPV, and NPV of 64SCT for the detection of significant in-stent disease was 75%, 92%, 89%, 67%, and 94%, respectively. Both occluded coronary artery stents were correctly identified. The sensitivity, specificity, and accuracy values of 64SCT for the detection of significant proximal peri-stent stenoses were 75%, 95%, and 93%, respectively, whereas the values for detection of significant distal peri-stent stenoses were 67%, 85%, and 84%, respectively.The high spatial and temporal resolution of 64SCT may permit improved assessment of stent occlusion and peri-stent disease, although detection of in-stent stenosis remains difficult.

View details for DOI 10.1016/j.acra.2006.09.044

View details for Web of Science ID 000242737000004

View details for PubMedID 17138114

Abstract

Multidetector row CT of the heart and coronary arteries is now a robust clinical method. It may be used in a number of different clinical scenarios, such as in the presence of an equivocal stress test or ambiguous clinical symptoms. Cardiac CT is also increasingly being developed as a diagnostic option for acute care such as in acute coronary syndrome. Here CT may serve as a tool to triage patients to appropriate therapy or to discharge them immediately after the investigation. The newest dual source CT also allows the assessment of cardiac function, helping to specify the diagnosis. Valve assessment by CT is still under investigation. However multidetector CT is of limited value in myocardial perfusion or for late my-ocardial enhancement scanning. Appropriate selection of patients for cardiac multidetector CT is mandatory so that the procedure is carried out only in those in whom it can provide clinically valuable information.

View details for PubMedID 18655269

Abstract

With the advances made in radiology and cardiology, greater numbers of patients are expected to undergo exposure to iodinated contrast media in the years to come. Contrast-induced nephropathy (CIN) accounts for a significant number of cases of hospital-acquired renal failure, with adverse effects on prognosis and healthcare costs. The CIN Consensus Working Panel is an international multidisciplinary group convened to address the challenges of CIN. The group reviewed 865 published papers, chosen for potential relevance from a comprehensive literature search that identified over 4000 references. The results were used to compile reviews covering the epidemiology and pathogenesis of CIN, baseline renal function measurement, risk assessment, identification of high-risk patients, contrast medium use, and preventive strategies. In this executive summary, consensus statements and an algorithm for the risk stratification and management of CIN are presented.

View details for Web of Science ID 000243285900001

View details for PubMedID 17224862

Abstract

With the wider use of imaging and interventional techniques that require the use of iodinated contrast media in seriously ill patients, many clinical situations occur where patients may be at increased risk for contrast-induced nephropathy (CIN). There is little guidance for clinicians in these areas. The aim of this review is to assess the available literature. Acute renal failure is a common complication following coronary artery bypass surgery, and exposure to contrast medium may increase the risk for this condition, although there is insufficient evidence to make a definitive statement. Evidence is also limited for patients with liver disease: in those undergoing transarterial chemoembolization, cirrhosis may be a risk factor for renal failure. There is some evidence that periprocedural hypotension may be a risk factor for CIN after percutaneous coronary intervention, but no published information was identified on the significance of shock or hypotension in other groups of patients. The published evidence on the risk of CIN in renal transplant recipients is inconsistent. In emergency situations, the course of action is usually dictated by clinical circumstances; the renal status of a patient is likely to be unknown and it is important to ensure adequate volume expansion, especially after the procedure. In all clinical situations that are potentially associated with a high risk for CIN, the decision to administer contrast medium is a matter for clinical judgment, based on the clinical status of the patient and the expected benefits of the investigation or procedure.

View details for DOI 10.1016/amjcard.2006.01.025

View details for Web of Science ID 000240840300007

View details for PubMedID 16949379

Abstract

Contrast-induced nephropathy (CIN), usually defined as an increase in serum creatinine of 0.5 mg/dL (44.2 mumol/L), or a 25% increase from the baseline value 48 hours after the procedure, is a common and potentially serious complication of the use of iodinated contrast media in patients at risk of acute renal injury. It is an important cause of hospital-acquired renal failure, responsible for approximately 11% of cases. CIN may be difficult to distinguish from cholesterol embolization, another cause of postprocedure renal impairment. The reported incidence of CIN varies depending on the patient population studied. The impact of postprocedural renal impairment on clinical outcomes has been evaluated most extensively in patients undergoing percutaneous coronary intervention. CIN is associated with increased mortality both in hospital and at 1 year. A higher incidence of in-hospital and late cardiovascular events, as well as longer hospital stays, has been reported in patients developing CIN. In a small proportion of patients, CIN is severe enough to require dialysis, and these patients have a particularly poor prognosis. Many of the risk markers for CIN are also predictive of a worse prognosis.

View details for DOI 10.1016/j.amjcard.2006.01.019

View details for Web of Science ID 000240840300003

View details for PubMedID 16949375

Abstract

Contrast-induced nephropathy (CIN) is the third leading cause of acute kidney injury in hospitalized patients and is associated with significant patient morbidity. The pathogenesis of CIN is complex and not fully understood, but iodinated contrast agents induce intense and prolonged vasoconstriction at the corticomedullary junction of the kidney. Moreover, high-osmolar dyes directly impair the autoregulatory capacity of the kidney through a loss of nitric oxide production. These effects, coupled with direct tubular toxicity of contrast media, lead to overt acute tubular necrosis and the syndrome of CIN.

View details for DOI 10.1016/j.amjcard.2006.01.020

View details for Web of Science ID 000240840300004

View details for PubMedID 16949376

Abstract

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.

View details for DOI 10.1016/j.amjcard.2006.01.023

View details for Web of Science ID 000240840300008

View details for PubMedID 16949380

Abstract

In order to make appropriate decisions about clinical management, it is important for physicians to be able to stratify patients according to their risk for contrast-induced nephropathy (CIN). The most important risk marker for nephropathy after exposure to iodinated contrast media is preexisting renal impairment. The risk of CIN is elevated and becomes clinically important in patients with chronic kidney disease characterized by an estimated glomerular filtration rate <60 mL/min per 1.73 m(2). In patients with renal impairment, diabetes mellitus amplifies the risk of CIN and complicates postprocedure management. Other markers associated with an increased risk of CIN include cardiovascular disease, periprocedural hemodynamic instability, use of nephrotoxic drugs, and anemia. The effect of risk factors is additive, and the presence of multiple risk factors in the same patient can create a very high risk for CIN and acute renal failure requiring dialysis. Risk models incorporating baseline and periprocedural characteristics have been developed using data from large databases of percutaneous coronary intervention patients. These schemes are potentially valuable, but at present the most practical approach to risk prediction is based on a simple model incorporating renal function and diabetes mellitus.

View details for DOI 10.1016/amjcard.2006.01.022

View details for Web of Science ID 000240840300006

View details for PubMedID 16949378

Abstract

In view of the clinical importance of contrast-induced nephropathy (CIN), numerous potential risk-reduction strategies have been evaluated. Adequate intravenous volume expansion with isotonic crystalloid (1.0-1.5 mL/kg per hr) for 3-12 hours before the procedure and continued for 6-24 hours afterward can lessen the probability of CIN in patients at risk. There are insufficient data on oral fluids (as opposed to intravenous volume expansion) as a CIN-prevention strategy. No adjunctive medical or mechanical treatment has been proved to be efficacious in reducing risk for CIN. Prophylactic hemodialysis and hemofiltration have not been validated as effective strategies. The CIN Consensus Working Panel considered that, of the pharmacologic agents that have been evaluated, theophylline, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), ascorbic acid, and prostaglandin E(1) deserve further evaluation. N-acetylcysteine is not consistently effective in reducing the risk for CIN. Fenoldopam, dopamine, calcium channel blockers, atrial natriuretic peptide, and l-arginine have not been shown to be effective. Use of furosemide, mannitol, or an endothelin receptor antagonist is potentially detrimental. Nephrotoxic drugs should be withdrawn before contrast administration in patients at risk for CIN.

View details for DOI 10.1016/j.amjcard.2006.01.024

View details for Web of Science ID 000240840300009

View details for PubMedID 16949381

Abstract

Renal impairment at baseline (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m(2)) is the most important risk marker to predict the risk of contrast-induced nephropathy (CIN) in patients receiving iodinated contrast media. Hence, it is important to assess renal function before administration of contrast medium to ensure that appropriate steps are taken to reduce the risk. Serum creatinine alone does not provide a reliable measure of renal function, hence the National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) recommends that clinicians should use an eGFR calculated from the serum creatinine as an index of renal function. The CIN Consensus Working Panel agreed that eGFR should be determined before contrast administration, using the abbreviated Modification of Diet in Renal Disease (MDRD) formula, recommended by K/DOQI as the preferred equation for the calculation of eGFR in adults. Where a serum creatinine measurement or eGFR is not available, a simple survey or questionnaire can be used before contrast agent administration to identify patients at higher risk for CIN compared with the general population. In emergency situations, where the benefit of very early imaging outweighs the risk of waiting, the CIN Consensus Working Panel agreed that the procedure can be performed without assessment of renal function.

View details for DOI 10.1016/j.amjcard.2006.01.021

View details for Web of Science ID 000240840300005

View details for PubMedID 16949377

View details for DOI 10.1016/j.acra.2006.06.006

View details for Web of Science ID 000240297100014

View details for PubMedID 16935729

Abstract

The purpose of our study was to evaluate the dose reduction potential of combined online (x- and y-axes) and topogram-based (l) X-ray tube current modulation in CT colonography in a screening population.Eighty asymptomatic individuals underwent CT colonography screening for colon polyps. A 16-MDCT scanner (Somatom Sensation 16) was used. Forty patients were examined at 120 kVp and 120 effective mAs (supine) and 40 effective mAs (prone) using online x- and y-axis tube current modulation. Another 40 patients were scanned using combined x-, y-, and z-axis tube current modulation. Individual patient radiation exposure was determined using the dose-length product. Image noise was determined by Hounsfield unit measurements in the colonic lumen at four anatomic levels. Image quality was rated on a 5-point confidence scale by two independent reviewers. The unpaired Student's t test (for radiation dose, image noise) and Wilcoxon's test (for image quality) were used to test for statistically significant differences between these values.Radiation dose was significantly lower in the patient group scanned with x-, y-, and z-axis tube current modulation than in the group scanned with x- and y-axis tube current modulation (supine: 4.24 vs 6.50 mSv, p < 0.0001; prone: 1.61 vs 2.38 mSv, p < 0.0001). Radiation dose was reduced by 35% (supine) and 33% (prone). No statistically significant difference was seen in overall image noise (supine: 15.9 vs 16.3 H, p = 0.13; prone: 23.5 vs 24.8 H, p = 0.44) or image quality (supine: 4.6 vs 4.5, p = 0.62; prone: 3.5 vs 3.6, p = 0.54).Combined x-, y-, and z-axis tube current modulation leads to a significant reduction of radiation exposure in CT colonography without loss of image quality.

View details for DOI 10.2214/AJR.05.0662

View details for Web of Science ID 000240259300018

View details for PubMedID 16928932

Abstract

The aim of the study was to evaluate the potential of new-generation multi-slice computed tomography (CT) scanner technology for the delineation of coronary artery stents in an ex vivo setting. Nine stents of various diameters (seven stents 3 mm, two stents 2.5 mm) were implanted into the coronary arteries of ex vivo porcine hearts and filled with a mixture of an iodine-containing contrast agent. Specimens were scanned with a 16-slice CT (16SCT) machine; (Somatom Sensation 16, Siemens Medical Solutions), slice thickness 0.75 mm, and a 64-slice CT (64SCT, Somatom Sensation 64), slice-thickness 0.6 mm. Stent diameters as well as contrast densities were measured, on both the 16SCT and 64SCT images. No significant differences of CT densities were observed between the 16SCT and 64SCT images outside the stent lumen: 265+/-25HU and 254+/-16HU (P=0.33), respectively. CT densities derived from the 64SCT images and 16SCT images within the stent lumen were 367+/-36HU versus 402+/-28HU, P<0.05, respectively. Inner and outer stent diameters as measured from 16SCT and 64SCT images were 2.68+/-0.08 mm versus 2.81+/-0.07 mm and 3.29+/-0.06 mm versus 3.18+/-0.07 mm (P<0.05), respectively. The new 64SCT scanner proved to be superior in the ex vivo assessment of coronary artery stents to the conventional 16SCT machine. Increased spatial resolution allows for improved assessment of the coronary artery stent lumen.

View details for DOI 10.1007/s00330-006-0186-5

View details for Web of Science ID 000238270300020

View details for PubMedID 16518653

Abstract

The relation of heart rate and image quality in the depiction of coronary arteries, heart valves and myocardium was assessed on a dual-source computed tomography system (DSCT). Coronary CT angiography was performed on a DSCT (Somatom Definition, Siemens) with high concentration contrast media (Iopromide, Ultravist 370, Schering) in 24 patients with heart rates between 44 and 92 beats per minute. Images were reconstructed over the whole cardiac cycle in 10% steps. Two readers independently assessed the image quality with regard to the diagnostic evaluation of right and left coronary artery, heart valves and left ventricular myocardium for the assessment of vessel wall changes, coronary stenoses, valve morphology and function and ventricular function on a three point grading scale. The image quality ratings at the optimal reconstruction interval were 1.24+/-0.42 for the right and 1.09+/-0.27 for the left coronary artery. A reconstruction of diagnostic systolic and diastolic images is possible for a wide range of heart rates, allowing also a functional evaluation of valves and myocardium. Dual-source CT offers very robust diagnostic image quality in a wide range of heart rates. The high temporal resolution now also makes a functional evaluation of the heart valves and myocardium possible.

View details for DOI 10.1007/s00330-006-0298-y

View details for Web of Science ID 000238270300001

View details for PubMedID 16770652

Abstract

The aim of this study was to evaluate the potential clinical value of a new generation of 64-MDCT systems with that of invasive coronary angiography in the diagnosis of coronary artery disease (CAD).Seventy-two consecutive patients with known or suspected CAD underwent both 64-MDCT and quantitative coronary angiography (QCA). A CT system with acquisition of 64 slices per gantry rotation was used with a spatial resolution of 0.4 x 0.4 x 0.4 mm and a gantry rotation time of 330 milliseconds. Sensitivity, specificity, and diagnostic accuracy of 64-MDCT in the detection or exclusion of CAD were evaluated on both a per patient and a per segment basis.Sixty-eight of 72 coronary CT angiograms (CTAs) (94%) were of diagnostic image quality. QCA showed significant CAD (i.e., one or more stenoses in > 50%) in 57% (39/68) and nonsignificant disease or healthy CTAs in 43% (29/68) of the patients. Sensitivity, specificity, and the negative predictive value (NPV) of 64-MDCT per patient were 97%, 79%, and 96%, respectively. Per segment, 923 of 1,020 coronary artery segments were assessable (90%). For the detection of stenoses of more than 50% and more than 75% per segment, 64-MDCT showed a sensitivity of 82% and 86%, respectively. Per segment, specificity and NPV were as high as 95% and 97%, respectively.In clinical routine, coronary CTA will primarily be used for risk stratification on a per patient basis. In the present study, coronary 64-MDCT showed a high diagnostic accuracy on both per patient and per segment analyses.

View details for DOI 10.2214/AJR.05.1697

View details for Web of Science ID 000238659600021

View details for PubMedID 16794164

Abstract

The aim of this study was to evaluate the clinical value of MDCT in the diagnosis of coronary artery disease in a population having a low pretest likelihood of significant disease.Sixty-four patients with suspected coronary artery disease and a low pretest likelihood of significant disease according to the criteria of the American Heart Association underwent both MDCT of the heart and quantitative conventional coronary angiography (QCA). MDCT examinations were performed on a 16-MDCT scanner. CT data sets were evaluated on a per-patient basis and a per-segment basis and were classified as indicating no disease, nonsignificant disease (stenoses 50%). Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of 16-MDCT in the detection or exclusion of significant and nonsignificant coronary artery disease were evaluated on both per-patient and per-segment bases.Regarding the success rate of 16-MDCT, 94% (60/64) of patients and 92% (388/420) of vessel segments were of sufficient quality for diagnosis. In the remaining 60 patients evaluated, QCA revealed significant coronary artery disease, nonsignificant disease, and no disease in 8.3% (5/60), 75.0% (45/60), and 16.7% (10/60) of cases, respectively, on a per-patient basis, and in 1.3% (5/388), 23.2% (90/388), and 75.5% (293/388) of cases, respectively, on a per-segment basis. The sensitivity, specificity, NPV, and PPV of 16-MDCT for the detection of significant coronary artery disease were 80.0%, 94.5%, 98.1%, and 57.1%, respectively, on a per-patient basis, and 80.0%, 99.2%, 99.7%, and 57.1% on a per-segment basis.In a population having a low pretest likelihood of significant coronary artery disease, 16-MDCT shows a moderate to high sensitivity and high NPV for the detection or exclusion of significant disease, but has a somewhat reduced PPV compared with QCA.

View details for DOI 10.2214/AJR.05.0726

View details for Web of Science ID 000237759300025

View details for PubMedID 16714656

Abstract

The aims of our study were to compare contrast injection protocols with contrast media containing 300 and 400 mg iodine per milliliter for optimal contrast enhancement in cardiac multidector row computed tomography (CT) and to evaluate the correlation of test bolus curve parameters with the final contrast density of the main bolus.Sixty patients with known or suspected coronary artery disease were included in a prospective double-blind study. Patients were randomized to 2 groups. Group 1 received 83 mL of a contrast medium (CM) containing 300 mg of iodine (Iomeron 300, Bracco Imaging SpA, Milan, Italy) at a flow rate of 3.3 mL/s, whereas group 2 received 63 mL of the same agent containing 400 mg of iodine (Iomeron 400) at a flow rate of 2.5 mL/s. The test bolus volumes were 20 mL and 15 mL, respectively. Imaging was performed using a 16-slice CT system (16DCT; Somatom Sensation 16, Siemens Medical Solutions, Forchheim, Germany). Contrast densities (Hounsfield Units [HU]) were determined in the cardiac chambers and in the main coronary arteries. The peak density and area under the curve of the test bolus were calculated for each patient.The mean contrast densities of the coronary arteries were 259.1 +/- 46.7 HU for group 1 and 251.6 +/- 51.0 HU, for group 2. No noteworthy differences between groups were noted for density measurements in the cardiac chambers or for the ratio of right-to-left ventricle density. Whereas a positive correlation was noted for both groups between the area under the curve of the test bolus and the mean density of the main bolus, a positive correlation between peak density of the test bolus and mean density of the main bolus was noted only for group 1.Equivalent homogenous enhancement of the ventricular cavities and coronary arteries to that obtained using a CM with standard iodine concentration (Iomeron 300) can be achieved with lower overall volumes of administered CM and reduced injection flow rates when a CM with high iodine concentration (Iomeron 400) is used.

View details for Web of Science ID 000237100600006

View details for PubMedID 16625109

Abstract

We evaluated the accuracy of a new 64-slice computed tomography (CT) scanner, compared with intravascular ultrasound, to visualize atherosclerosis in the proximal coronary system.Noninvasive determination of plaque composition and plaque burden may be important to improve risk stratification.In 20 patients, a 64-slice CT scan (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) and an intravascular ultrasound investigation of vessels without stenosis >50% was performed. Diagnostic image quality with 64-slice CT was obtained in 36 vessels in 19 patients.In these vessels, which were divided in 3-mm sections, 64-slice CT enabled a correct detection of plaque in 54 of 65 (83%) sections containing noncalcified plaques, 50 of 53 (94%) sections containing mixed plaques, and 41 of 43 (95%) sections containing calcified plaques. In 192 of 204 (94%) sections, atherosclerotic lesions were excluded correctly. In addition, 64-slice CT enabled the visualization of 7 of 10 (70%) sections revealing a lipid pool and could identify a spotty calcification pattern in 27 of 30 (90%) sections. The correlation coefficient to determine plaque volumes per vessel was r2 = 0.69 (p < 0.001) with an underestimation of mixed and noncalcified plaque volumes (p < 0.03) and a trend to overestimate calcified plaque volumes by 64-slice CT. The interobserver variability to determine plaque volumes was 37%. Interobserver agreement to identify atherosclerotic sections was good (Cohen's kappa coefficient = 0.75).We conclude that 64-slice CT reveals encouraging results to noninvasively detect different types of coronary plaques located in the proximal coronary system. The ability to determine plaque burden currently is hampered by mainly an insufficient reproducibility.

View details for DOI 10.1016/j.jacc.2005.10.058

View details for Web of Science ID 000235198000030

View details for PubMedID 16458154

Abstract

We present a performance evaluation of a recently introduced dual-source computed tomography (DSCT) system equipped with two X-ray tubes and two corresponding detectors, mounted onto the rotating gantry with an angular offset of 90 degrees . We introduce the system concept and derive its consequences and potential benefits for electrocardiograph [corrected] (ECG)-controlled cardiac CT and for general radiology applications. We evaluate both temporal and spatial resolution by means of phantom scans. We present first patient scans to illustrate the performance of DSCT for ECG-gated cardiac imaging, and we demonstrate first results using a dual-energy acquisition mode. Using ECG-gated single-segment reconstruction, the DSCT system provides 83 ms temporal resolution independent of the patient's heart rate for coronary CT angiography (CTA) and evaluation of basic functional parameters. With dual-segment reconstruction, the mean temporal resolution is 60 ms (minimum temporal resolution 42 ms) for advanced functional evaluation. The z-flying focal spot technique implemented in the evaluated DSCT system allows 0.4 mm cylinders to be resolved at all heart rates. First clinical experience shows a considerably increased robustness for the imaging of patients with high heart rates. As a potential application of the dual-energy acquisition mode, the automatic separation of bones and iodine-filled vessels is demonstrated.

View details for DOI 10.1007/s00330-005-2919-2

View details for Web of Science ID 000234755200001

View details for PubMedID 16341833

Abstract

We wanted to determine the rate of contrast-induced nephropathy (CIN) caused in patients with renal impairment undergoing multidetector row computed tomography (MDCT) angiography with intravenous administration of iso-osmolar dimeric contrast media (iodixanol).The first consecutive 100 patients referred to CT with a serum creatinine level (SCr) between 1.5 and 6 mg/dL were enrolled in the study. Serum creatinine also was determined on days 3 and 7 after the intravenous administration of 100 mL of iodixanol 270 with 5 mL/s. A CIN was considered if variation of SCr on day 3 was >0.5 mg/dl above baseline.Nine patients developed a CIN after MDCT angiography; 7 of them recovered completely by day 7, and the remaining 2 showed elevated SCr on day 7 but did not develop renal failure during their hospital stay.MDCT angiography performed in patients with impaired renal function with iodixanol may result in CIN but complete recovery is probable.

View details for Web of Science ID 000232212600007

View details for PubMedID 16189436

Abstract

Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has delivered promising accuracy in the detection and validation of coronary lesions. Myocardial perfusion imaging (MPI) using SPECT is an established method for noninvasively assessing the functional significance of coronary stenoses and delivers valuable information for risk stratification. This retrospective analysis compared the accuracies of MDCT angiography and MPI in the detection of hemodynamically relevant lesions of the coronary arteries.Twenty-five patients with suspected or known coronary artery disease were studied. Electrocardiographically gated MPI and 16-MDCT angiography were performed. Myocardial perfusion images were analyzed by 2 experienced observers, and reversible and fixed perfusion defects were detected and allocated to their corresponding coronary vessels. For the evaluation of MDCT angiography, image quality was determined, and lesions > or = 50% and luminal narrowing < 50% were visually assessed and characterized by 2 independent observers unaware of the results of MPI.Ninety-nine coronary vessels were analyzed, and the quality of MDCT angiography images was assessed for 330 coronary segments. Coronary artery diameter was interpretable for 231 (70%) of 330 segments, whereas in 99 (30%) of 330 segments, vessel diameter could not be evaluated because of heavy calcifications, blurring, motion artifacts, or intracoronary stents. MDCT angiography detected stenoses > or = 50% in 15 of 100 coronary arteries. Eight (53%) of 15 stenoses > or = 50% showed reversible or fixed perfusion defects in the corresponding myocardial areas on MPI. Sensitivity, specificity, and negative and positive predictive values were 100%, 87%, 100%, and 29%, respectively, for the ability of MDCT angiography to detect reversible perfusion defects in the corresponding myocardial areas.MDCT angiography detected myocardial ischemia, as defined by reversible perfusion defects on MPI, with a positive predictive value of 29% in a nonselected study cohort. Compared with MPI alone, MDCT angiography added important morphologic information, but MPI remains mandatory for evaluating the functional relevance of coronary artery lesions.

View details for Web of Science ID 000231102000012

View details for PubMedID 16085585

View details for PubMedID 16043650

Abstract

The aim of the present study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) to identify and quantify atherosclerotic coronary lesions in comparison with catheter-based angiography and intravascular ultrasound (IVUS).Currently, the ability of multislice CT to quantify the degree of coronary artery stenosis and dimensions of coronary plaques has not been evaluated.We included 59 patients scheduled for coronary angiography due to stable angina pectoris. A contrast-enhanced 64-slice CT (Senation 64, Siemens Medical Solutions, Forchheim, Germany) was performed before the invasive angiogram. In a subset of 18 patients, IVUS of 32 vessels was part of the catheterization procedure.In 55 of 59 patients, 64-slice CT enabled the visualization of the entire coronary tree with diagnostic image quality (American Heart Association 15-segment model). The overall correlation between the degree of stenosis detected by quantitative coronary angiography compared with 64-slice CT was r = 0.54. Sensitivity for the detection of stenosis <50%, stenosis >50%, and stenosis >75% was 79%, 73%, and 80%, respectively, and specificity was 97%. In comparison with IVUS, 46 of 55 (84%) lesions were identified correctly. The mean plaque areas and the percentage of vessel obstruction measured by IVUS and 64-slice CT were 8.1 mm2 versus 7.3 mm2 (p < 0.03, r = 0.73) and 50.4% versus 41.1% (p < 0.001, r = 0.61), respectively.Contrast-enhanced 64-slice CT is a clinically robust modality that allows the identification of proximal coronary lesions with excellent accuracy. Measurements of plaque and lumen areas derived by CT correlated well with IVUS. A major limitation is the insufficient ability of CT to exactly quantify the degree of stenosis.

View details for DOI 10.1016/j.jacc.2005.03.071

View details for Web of Science ID 000230216000023

View details for PubMedID 15992649

Abstract

The broad introduction of multi-slice CT by all major vendors in 1998 was a milestone with regard to extended volume coverage, improved axial resolution and better utilization of the tube output. New clinical applications such as CT-examinations of the heart and the coronary arteries became possible. Despite all promising advances, some limitations remain for 4-slice CT systems. They come close to isotropic resolution, but do not fully reach it in routine clinical applications. Cardiac CT-examinations require careful patient selection. The new generation of multi-slice CT-systems offer simultaneous acquisition of up to 16 sub-millimeter slices and improved temporal resolution for cardiac examinations by means of reduced gantry rotation time (0.4 s). In this overview article we present the basic technical principles and potential applications of 16-slice technology for the example of a 16-slice CT-system (SOMATOM Sensation 16, Siemens AG, Forchheim). We discuss detector design and dose efficiency as well as spiral scan- and reconstruction techniques. At comparable slice thickness, 16-slice CT-systems have a better dose efficiency than 4-slice CT-systems. The cone-beam geometry of the measurement rays requires new reconstruction approaches, an example is the adaptive multiple plane reconstruction, AMPR. First clinical experience indicates that sub-millimeter slice width in combination with reduced gantry rotation-time improves the clinical stability of cardiac examinations and expands the spectrum of patients accessible to cardiac CT. 16-slice CT-systems have the potential to cover even large scan ranges with sub-millimeter slices at considerably reduced examination times, thus approaching the goal of routine isotropic imaging.

View details for DOI 10.1007/s00117-003-0944-1

View details for Web of Science ID 000231299700003

View details for PubMedID 16059657

Abstract

To assess the diagnostic accuracy of 16-detector-row computed tomography (16DCT) of the heart in the assessment of myocardial perfusion and viability in comparison to stress perfusion magnetic resonance imaging (SP-MRI) and delayed-enhancement magnetic resonance imaging (DE-MRI). A number of 30 patients underwent both 16DCT and MRI of the heart. Contrast-enhanced 16DCT data sets were reviewed for areas of myocardium with reduced attenuation. Both CT and MRI data were examined by independent reviewers for the presence of myocardial perfusion defects or myocardial infarctions (MI). Volumetric analysis of the hypoperfusion areas in CT and the infarct sizes in DE-MRI were performed. According to MRI, myocardial infarctions were detected in 11 of 30 cases, and perfusion defects not corresponding to an MI were detected in six of 30 patients. CTA was able to detect ten of 11 MI correctly (sensitivity 91%, specificity 79%, accuracy 83%), and detected three of six hypoperfusions correctly (sensitivity 50%, specificity 92%, accuracy 79%). Assessing the volume of perfusion defects correlating to history of MI on the CT images, a systematic underestimation of the true infarct size as compared to the results of DE-MRI was found (P<0.01). Routine, contrast-enhanced 16-detector row CT of the heart can detect chronic myocardial infarctions in the majority of cases, but ischemic perfusion defects are not reliably detected under resting conditions.

View details for DOI 10.1007/s00330-005-2672-6

View details for Web of Science ID 000229296900002

View details for PubMedID 15776243

Abstract

Evaluation of left ventricular function using electrocardiogram (ECG)-gated multidetector row CT (MDCT) by using 3 different volumetric assessment methods in comparison to assessment of the left ventricular function by invasive ventriculography.Thirty patients with suspected or known coronary artery disease underwent MDCT coronary angiography with retrospective ECG cardiac gating. Raw data were reconstructed at the end-diastolic and end-systolic periods of the heart cycle. To calculate the volumes of the left ventricle, 3 methods were applied: The 3-dimensional data set (3D), the geometric hemisphere cylinder (HC), and the geometric biplane ellipsoid (BE) methods. End-diastolic volumes (EDV), end-systolic volumes (ESV), the stroke volumes (SV), and ejection fractions (EF) were calculated. The left ventricular volumetric data from the 3 methods were compared with measurements from left ventriculography (LVG).The best results were obtained using the 3D method; EDV (r = 0.73), ESV (r = 0.88), and EF (r = 0.76) correlated well with the LVG data. The EDV volumes did not differ significantly between LVG and the 3D method (P = 0.24); however, ESV, SV, and EF differed significantly. The ESV were significantly overestimated (P < 0.01), leading to an underestimation of the SV (P < 0.01) and the EF (P < 0.01). The HC method resulted in the greatest overestimation of the volumes. The EDV and the ESV were 31.8 +/- 37.6% and 136.4 +/- 92.9% higher than the EDV and ESV volumes obtained by LVG. Bland-Altman analysis showed systematic overestimation of the ESV using the HC method.MDCT with retrospective cardiac ECG gating allows the calculation of left ventricular volumes to estimate systolic function. The 3D method had the highest correlation with LVG. However, the overestimation of the ESV is significant, which led to an underestimation of the SV and the EF.

View details for Web of Science ID 000229458400019

View details for PubMedID 15891510

Abstract

Coronary calcifications are specific markers for coronary atherosclerosis. The amount of coronary calcium is related to the likelihood of vulnerable plaques. Vulnerable plaques may rupture and may result in sudden coronary thrombus formation, occlusion, ischemia and ventricular fibrillation and finally cardiac death. Therefore, it is reasonable to believe that the risk of cardiac events can be assessed by the quantification of the extent of coronary calcium. However, until now, the predictive value of coronary calcium and the advantage over conventional risk factors has not yet been proven by any prospective cohort study. In practice uncertainty exists in the group of patients with an intermediate risk for cardiac events. In this particular cohort it is likely that the assessment of coronary atherosclerosis may help in the decision to initiate or discard a specific therapy. For this purpose it has been suggested to replace the Framingham age score by a score corrected by the amount of coronary calcium. Follow-up investigations may be helpful in the short term to determine the efficiency of different therapeutical options. To determine a significant progression of the amount of coronary calcium, the absolute mass should be determined in a period of 1 year.

View details for DOI 10.1007/s10406-005-0091-z

View details for Web of Science ID 000232376500004

View details for PubMedID 15801053

Abstract

The currently best available spatial and temporal resolution for retrospectively ECG gated coronary multi-detector-row CT angiography is 0.4 mm and 165 ms, respectively. These acquisition parameters are already rather close to cardiac catheter. Studies so far compared non-invasive coronary CT and convention angiography for the detection of coronary artery stenoses. The most promising result reported by all authors was the high negative predictive value of the CTA. It now needs to be determined if CTA is a reliable tool to rule out coronary artery stenoses in a patient cohort with low likelihood of CAD, such as those with atypical chest pain or ambiguous stress test. CTA may furthermore establish as a rapid and widely available tool to detect vulnerable plaques or intracoronary thrombus in patients with acute coronary syndrome and unstable angina. In patients with chronic stable angina, tools that determine myocardial ischemia under stress such as SPECT and MRI are probably better suited to determine the relevance of coronary artery stenoses. In this particular cohort, by displaying the extent and morphology of coronary atherosclerosis, CTA may help to direct the therapy to either intervention or surgery.

View details for DOI 10.1007/s10406-005-0095-8

View details for Web of Science ID 000232376500006

View details for PubMedID 15801055

Abstract

The aim of the study was to implement an abdominal CT angiography protocol using 100 kVp and to compare SNR and CNR, as well as subjective image quality, to a standard CT angiography protocol using 120 kVp on a 16 detector-row CT scanner. Forty-eight patients were referred for routine abdominal CT angiography on a 16 detector-row CT scanner. Patients were scanned using either 120 or 100 kVp at constant mAs settings. Vessel opacification was provided by automated contrast injection using similar injection protocols. Density measurements were performed along the aorto-iliac axis with SNR and CNR calculation. In addition, the estimated effective patient radiation dose was calculated. Results of both protocols were compared. The 100-kVp protocol (432+/-80 HU) showed a significantly higher vessel density than the 120-kVp (333+/-90 HU; P<0.001) protocol, corresponding to an average increase in signal intensity of 30.7%. SNR (36.0 vs 37.0) and CNR (31.1 vs 31.7) for the 100-kV protocol were not significantly lower that those for the standard protocol (P=0.79 and P=0.87), whilst the average estimated dose was significantly lower using the 100-kVp protocol (6.7+/-0.4 vs 10.1+/-1.2 mSv; P<0.0001). Tube kVp reduction from 120 to 100 kVp allows for significant reduction of patient dose in abdominal CT angiography, without significant change in SNR,CNR and image quality.

View details for DOI 10.1007/s00330-004-2575-y

View details for Web of Science ID 000227333900020

View details for PubMedID 15611872

Abstract

Due to a rapid improvement of the new generation submillimetre multislice CT-technology noninvasive tomographic imaging of the coronary vessel wall has become reality. First clinical studies have shown the ability in particular of 16-slice CT to determine plaque burden, plaque composition and compensatory vessel-wall remodelling. These novel findings already constitute an important step forward to assess coronary atherosclerosis noninvasively in a detailed manner which opens promising new opportunities for a better understanding and riskstratification of coronary atherosclerosis. Current limitations, mainly the insufficient accuracy to detect small lesions in distal coronary segments, might be overcome by improved spatial and temporal resolution of the new generation scanners operating with 64 and more detectors.

View details for DOI 10.1007/s10554-004-5337-7

View details for Web of Science ID 000229116200007

View details for PubMedID 15915940

Abstract

The aim of this technical investigation was the detailed description of a prototype flat panel detector computed tomography system (FPCT) and its initial evaluation in an ex vivo setting. The prototype FPCT scanner consists of a conventional radiographic flat panel detector, mounted on a multi-slice CT scanner gantry. Explanted human ex vivo heart and foot specimens were examined. Images were reformatted with various reconstruction algorithms and were evaluated for high-resolution anatomic information. For comparison purposes, the ex vivo specimens were also scanned with a conventional 16-detector-row CT scanner (Sensation 16, Siemens Medical Solutions, Forchheim, Germany). With the FPCT prototype used, a 1,024x768 resolution matrix can be obtained, resulting in an isotropic voxel size of 0.25x0.25x0.25 mm at the iso-center. Due to the high spatial resolution, very small structures such as trabecular bone or third-degree, distal branches of coronary arteries could be visualized. This first evaluation showed that flat panel detector systems can be used in a cone-beam computed tomography scanner and that very high spatial resolutions can be achieved. However, there are limitations for in vivo use due to constraints in low contrast resolution and slow scan speed.

View details for DOI 10.1007/s00330-004-2537-4

View details for Web of Science ID 000227333900019

View details for PubMedID 15662479

Abstract

Coronary calcium mass percentiles can be derived from electron beam CT as well as from multidetector-row CT of all manufacturers. Coronary calcium mass may serve as a more individualized substitute for age for cardiac risk stratification. The aim was to investigate the potential impact of CT coronary calcium mass quantification on cardiac risk stratification using an adjusted Framingham score. Standardized coronary calcium mass was determined by multidetector-row CT in a total of 1,473 patients (1,038 male, 435 female). The impact on risk stratification of replacing the traditional Framingham age point score by a point score based on calcium mass relative to age was tested. Any coronary calcium found in males in the age group of 20-34 years and females in the age group of 20-59 years results in an increase of the Framingham score by 9 and 4-7 points, respectively. Only in males 65 years of age and older, none or minimal amounts of coronary calcium decrease the Framingham score by three points. The coronary calcium mass and age-related scoring system may have impact on the reassignment of patients with an intermediate Framingham risk to a lower or higher risk group.

View details for DOI 10.1007/s00330-004-2528-5

View details for Web of Science ID 000227354900015

View details for PubMedID 15549320

Abstract

Clinical progress by the development of multi-slice CT (MSCT) technology beyond 16 slices can more likely be expected from further improved spatial and temporal resolution rather than from a mere increase in the volume coverage speed. We present an evaluation of a recently introduced 64-slice CT (64SCT) system, which makes use of a periodic motion of the focal spot in the longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices.A recently introduced 64SCT system (SOMATOM Sensation 64, Siemens Medical Solutions, Forchheim, Germany) is being described and tested in first clinical practice, applying the following parameters: z-flying focal spot technology, 64 x 0.6 mm slices; spatial resolution, 0.4 x 0.4 x 0.4 mm; gantry rotation time, 330 ms; temporal resolution, 83-165 ms. Various phantom studies and first clinically implemented protocols are being described, to evaluate the full spectrum of possible applications for this scanner type, with a focus on cardiac imaging.ECG-gated cardiac scanning with this 64-slice CT system benefits clearly from both the improved temporal resolution and improved spatial resolution. These benefits enable a more reliable assessment of mixed plaques, due to reduced partial-voluming and beam-hardening artefacts caused by calcifications, and holds great promise for the reliable assessment of in-stent stenoses, as stent lumen visibility is clearly improved as compared to earlier MSCT systems. With the increased volume coverage and acquisition speed of the 64SCT system, a comprehensive emergency protocol of the thorax becomes feasible within an acceptable breath-hold time, performing an ECG-gated CT angiography of the complete thoracic vasculature. This protocol enables a detailed assessment of the thoracic aorta, the pulmonary arteries and the coronary arteries in one single examination.64SCT Cardiac imaging provides an increased spatial resolution with an isotropic voxel size of 0.4 mm and an improved temporal resolution of 83-165 ms. These benefits hold great promise especially for fast-moving organs requiring detailed imaging, such as the heart and coronary arteries.

View details for DOI 10.1007/s10554-004-7015-1

View details for Web of Science ID 000227364200014

View details for PubMedID 15856639

Abstract

Electron beam tomography (EBT) has been scientifically evaluated to a much lesser degree for non-cardiac indications than for cardiac purposes. Therefore, four groups of investigators in Berlin (2), Mannheim and Munchen, which were supported by the Deutsche Forschungsgemeinschaft (DFG), included applications outside the heart in their evaluation of EBT technology. EBT has proven useful to look for pulmonary embolism and to assess other vessels (aorta, aortic branches, and intracranial arteries). Imaging of the lung parenchyma benefits from its intrinsic high contrast and from the fast data acquisition of EBT. Limited photon efficiency, higher radiation exposure, increased noise levels and other artifacts, however, markedly reduce the value of EBT for imaging of low contrast objects compared to conventional spiral CT and multislice CT (MSCT), compromising, in particular, the morphologic depiction of parenchymal abdominal organs and the brain. Consequently, scientific studies to further evaluate EBT for scanning of the brain and parenchymal abdominal organs were not pursued. Radiation exposure for non-cardiac EBT studies is up to three times higher than that for respective spiral CT studies, and in children EBT can only be advocated in select cases. Radiation exposure for the various prospectively triggered cardiac examination protocols of EBT is lower than that for conventional coronary angiography. Radiation exposure in cardiac multislice CT exceeds severalfold that of EBT, but the dose efficiency of EBT and MSCT are similar due to higher spatial resolution and less image noise of MSCT. In addition, modifications of MSCT (ECG pulsing) can further reduce radiation exposure to the level of EBT. Technical improvements of the EBT successor scanner "e-Speed" enable faster data acquisition at higher spatial resolution. Within comparative studies, the "e-Speed" will have to prove its value and competitiveness, particularly in comparison with multislice CT. After profound scientific assessment in a multicenter evaluation supported by the Deutsche Forschungsgemeinschaft (DFG) and regardless of the specific suitability of electron beam tomography for various cardiac and some non-cardiac indications, the investigators unanimously find the electron beam tomograph Evolution C150 XP not suitable as a whole body CT scanner.

View details for DOI 10.1055/s-2004-813666

View details for Web of Science ID 000224904900006

View details for PubMedID 15497074

Abstract

Assessment of atherosclerotic plaque burden may help to further stratify asymptomatic subjects with an intermediate cardiac event risk according to their conventional risk factors. Coronary calcium screening is a simple and effective method to noninvasively assess the atherosclerotic plaque burden. Standardized quantification of the coronary calcium mass will allow the results of ongoing prospective cohort studies to be used for any computed tomography (CT) scanner, electron-beam CT, as well as multidetector-row CT. Coronary multidetector-row CT angiography may have the potential to visualize vulnerable plaques that are prone to rupture and cause acute coronary symptoms. However, neither the reliability of detection nor the strategies for intervention of vulnerable plaques with multidetector-row CT have to date been proven.

View details for PubMedID 15350173

Abstract

To optimize a methodology for ex vivo imaging of atherosclerotic vessel wall changes using multidetector-row computed tomography (MDCT) and multi-contrast magnetic resonance imaging (MRI).In phantom studies and studies on intact ex vivo porcine and human hearts, various filling mixtures of MDCT and MRI contrast agents have been evaluated, to enable filling and distension of the coronary arteries for optimal visualization of atherosclerotic vessel wall changes with both techniques. Various proportions of methyl cellulose, iodine-containing CT contrast agent and paramagnetic MR contrast agent containing iron-oxide particles have been tested. Imaging parameters have been optimized for high resolution plaque imaging using a four detector-row CT scanner and a 1.5 T MR system.Phantom studies and studies on ex vivo porcine and human hearts demonstrated optimal proportion of methyl cellulose and CT contrast agent to be 98% vs. 2%, and 75% vs. 25% of methyl cellulose vs. MR contrast agent, respectively. These proportions provided optimal opacification of the vessel lumen in the MDCT images with 250 Hounsfield Units, and good signal suppression within the vessel lumen in the MR images, resembling in vivo imaging techniques. After retrospective matching with histopathology, atherosclerotic lesions of the human ex vivo specimens could be identified on MRI and MDCT images.Using an optimized mixture of methyl cellulose, MDCT and MRI contrast agents, visualization of atherosclerotic vessel wall changes is feasible, and applicable to various ex vivo models.

View details for Web of Science ID 000223919800015

View details for PubMedID 15529917

Abstract

The socioeconomic importance of heart disease provides considerable motivation for development of radiologic tools for noninvasive imaging of the coronary arteries. Current computed tomographic (CT) techniques combine high speed and spatial resolution with sophisticated electrocardiographic synchronization and robustness of use. Application of these modalities for evaluation of coronary artery disease is a topic of active current research. Coronary artery calcium measurements with different CT techniques have been used for determining the risk of coronary events, but the exact role of this marker for cardiac risk stratification remains unclear pending results of population-based studies. Contrast material-enhanced CT coronary angiography has become an established clinical indication for some scenarios (eg, coronary artery anomalies, bypass patency, surgical planning). With current technology, the accuracy of CT coronary angiography for detection of coronary artery stenoses appears promising enough to warrant pursuit of this application, but sensitivity is still not high enough for routine diagnostic needs. The high negative predictive value of a normal CT coronary angiogram, however, may be useful for reliable exclusion of coronary artery stenosis. The cross-sectional nature of CT may allow noninvasive assessment of the coronary artery wall. Use of contrast-enhanced CT coronary angiography for detection, characterization, and quantification of atherosclerotic changes and total disease burden in coronary arteries as a potential tool for cardiac risk stratification is currently being investigated.

View details for DOI 10.1148/radiol.2321030636

View details for Web of Science ID 000222161300004

View details for PubMedID 15220491

Abstract

In the present study, we tested the ability of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI) to identify and retrospectively characterize atherosclerotic lesions in human ex vivo coronary arteries. Thirteen ex vivo hearts were studied with MDCT and MRI. MDCT-images were obtained with an isotropic voxel size of 0.6mm(3). MR images were obtained with an in-plane resolution of 195 microm and 3mm slice thickness. All images were matched with histopathology sections. For both modalities, the sensitivity for the detection of any atherosclerotic lesion was evaluated, and a retrospective analysis of plaque morphology according to criteria defined by the American Heart Association (AHA) was performed. At histopathology, 28 atherosclerotic lesions were found. 21 and 23 of these lesions were identified by MDCT and MRI, respectively. Both modalities detected a small number of false-positive lesions. After retrospective matching with histopathology, MDCT as well as MRI were able to differentiate typical morpholocigal features for fatty, fibrous or calcified plaque components. Using the information presented in this study, in vivo coronary artery wall imaging using MDCT as well as MRI could be facilitated and supported for future investigations on this subject.

View details for DOI 10.1016/j.atherosclerosis.2004.01.041

View details for Web of Science ID 000221674200006

View details for PubMedID 15136054

Abstract

In the United States, more than 1 million diagnostic invasive coronary angiograms are performed annually, and in about 50% the investigation is followed by an interventional procedure. The remaining symptomatic patients after angiography are treated conservatively or by bypass graft surgery. In recent decades coronary angiography has advanced to a fast and safe investigation. Nevertheless, in particular, patients are well aware of the small but not negligible risk of complications and the discomfort of the invasive procedure. In addition to electrocardiogram (EKG) or ultrasound stress test and thallium scintigraphy, there is further need for another noninvasive method that displays the morphology of the coronary arteries in a way that would allow the triage of patients with suspicion of coronary artery disease (CAD) for a conservative, interventional, or surgical treatment.

View details for Web of Science ID 000221845000004

View details for PubMedID 15170776

Abstract

This angiographically correlated study reports on, for the first time, age- and gender-based distribution of the volumetric calcium score in a large group of patients with suspected coronary artery disease. Volumetric calcium data predicted significant coronary artery disease (>/=50% lumen diameter stenosis) as well as the traditional Agatston score. Exclusion of any calcium was highly accurate in ruling out obstructive disease in symptomatic subjects >/=50 years of age.

View details for DOI 10.1016/j.amjcard.2004.01.044

View details for Web of Science ID 000221140100014

View details for PubMedID 15110209

Abstract

We evaluated the accuracy of contrast-enhanced multidetector spiral computed tomography (MDCT) for the noninvasive detection and classification of coronary plaques and compared it with intracoronary ultrasound (ICUS).Noninvasive determination of plaque composition and plaque burden may be important to improve risk stratification and to monitor progression of coronary atherosclerosis.We included 46 consecutive patients with a distinctive risk profile, who were investigated by ICUS (Goldvision, 20 MHz, Jomed Inc., Rancho Cordova, California). Due to the inability to slow the heart rate below 65 beats/min (n = 7) and due to renal insufficiency (n = 2), nine of 46 consecutive patients could not be studied by MDCT (Sensation 16, Siemens, Forchheim, Germany).In the remaining 37 patients, 68 vessels were investigated by ICUS, and 58 of these vessels were visualized by MDCT with image quality sufficient for analysis. In these vessels that were divided in 3-mm sections, MDCT correctly classified 62 of 80 (78%) sections containing hypoechoic plaque areas, 87 of 112 (78%) sections containing hyperechoic plaque areas, and 150 of 158 (95%) sections containing calcified plaque tissue. In 484 of 525 (92%) sections, atherosclerotic lesions were correctly excluded. The MDCT-derived density measurements within coronary lesions revealed significantly different values for hypoechoic (49 HU [Hounsfield Units] +/- 22), hyperechoic (91 HU +/- 22), and calcified plaques (391 HU +/- 156, p < 0.02).This study demonstrates that, in the case of diagnostic image quality, contrast-enhanced MDCT permits an accurate identification of coronary plaques and that computed tomography density values measured within plaques reflect echogenity and plaque composition.

View details for DOI 10.1016/j.jacc.2003.10.059

View details for Web of Science ID 000220640400019

View details for PubMedID 15063437

Abstract

With the design and development of advanced computed tomography (CT) techniques and applications, like the newest generation of 16-detector-row CTs, CT angiography of the lower limb becomes a feasible tool for imaging peripheral vascular disease. Due to several advantages, compared with conventional digital subtraction angiography (DSA), including minimal invasiveness, CT angiography competes against diagnostic DSA in several clinical situations. 16-DCT offers the possibility to acquire thin slices from the diaphragm to the ankle in less than 40 sec. Easily, a data set of 800 to 1200 transverse slices may be created. To use transverse reconstructions alone to read these volumetric data sets is not appropriate. Powerful post-processing tools for volumetric analysis are required so that routine interpretation can be performed as efficiently and accurately as transverse section review. Because of its widespread availability and applicability, CT angiography of the lower extremities may be applied to patients in a pre- or post-procedural situation and also serves as a first line modality in patients with acute onset of clinical symptoms. Although multidetector CT arteriography is rapidly achieving clinical acceptance, further studies need to be performed to fully evaluate the clinical value of this method of peripheral arterial imaging. This article reviews the current status of multidetector CT peripheral arteriography, including indications, technical details, image post-processing, radiation exposure, and clinical results.

View details for DOI 10.1053/j.sult.2004.02.003

View details for Web of Science ID 000221353800006

View details for PubMedID 15160795

Abstract

To evaluate the diagnostic power of contrast-enhanced multidetector-row computed tomography (MDCT) in assessing the presence, age, and size of myocardial infarctions.One hundred six patients underwent standard MDCT coronary angiography without additional changes in the protocol. In all patients, a complete patient history and left heart catheterization with biplane contrast ventriculography were available. The MDCT images were reviewed for the presence and age of myocardial infarctions in a blinded fashion. Infarct areas were detected as regions of reduced uptake of contrast in the early arterial phase and/or regional wall thinning. Reviewing the computed tomography (CT) images, CT density values (Hounsfield units [HU]) were measured at the site of infarcted and noninfarcted myocardium, and a volumetric assessment of the infarct size was performed.In 27 of 106 patients, myocardial infarctions were present. Multidetector-row computed tomography detected 23 of 27 infarctions (sensitivity of 85%, specificity of 91%, and accuracy of 90%). Comparing the HU of infarcted versus noninfarcted myocardium, the mean HU of infarcted areas was 54 +/- 19 HU versus 117 +/- 28 HU for noninfarcted myocardium (P < 0.01). Multidetector-row computed tomography was able to differentiate between recent and chronic infarctions. The infarct volumes of recent infarctions (6.3 +/- 3.6 cm) showed a negative correlation to the ejection fraction (EF) according to contrast ventriculography (ie, the larger the infarct volumes as measured using MDCT, the worse was the EF [r = -0.72, P < 0.01]).Performing standard MDCT coronary angiography, areas of infarcted myocardium can be identified with moderate to high sensitivity, without additional scanning or contrast administration. Infarct localization can be assessed accurately as compared with cineventriculography. To some degree, infarct age and infarct volume can be estimated.

View details for Web of Science ID 000220268800021

View details for PubMedID 15091136

Abstract

Within recent years, technical developments of multidetector-row CT (MDCT) have dramatically changed the application of CT angiography in the assessment of abdominal vascular pathologies. The simultaneous acquisition of multiple thin collimated slices in combination with enhanced gantry rotation speed offers thin slice coverage of extended volumes without any loss in spatial resolution. Using 4 detector-row CT scanners, the scan volume still has to be restricted and focused on dedicated abdominal vessel territories in order to provide high spatial resolution (1-2 mm), while 16 detector-row technology now enables full abdominal coverage from the diaphragm to the groin with full spatial resolution. Therefore, comprehensive CT angiography of the abdomen can be performed without the necessity of focusing on any vascular territory. This technique enables the evaluation of the whole arterial visceral vasculature (e.g., hepatic vessels, mesenteric vessels, renal arteries) and the aortic-iliac axis in a single data acquisition.

View details for DOI 10.1053/S0887-2171(03)00110-0

View details for Web of Science ID 000189276500004

View details for PubMedID 15035530

Abstract

The newest generation of 16-detector-row CT allows displaying the anatomy and assessment of coronary artery disease (CAD) when slow regular sinus rhythm is present.For morphological assessment of cardiac structures by using Multi-detector row CT a dedicated scan protocol is obligatory. The indication for coronary CT angiography (CTA) is currently under investigation by several study groups.Because of the limited spatial and temporal resolution and coronary calcium artefacts, it is not possible with multislice CT angiography to assess coronary arteries in patients with established coronary artery disease. The anatomy of the coronary arteries can well be displayed with this technique.The high negative predictive value of coronary CTA may justify the investigation of symptomatic patients with intermediate pretest probability of CAD. Moreover coronary CTA is suitable for patients for displaying the origin and course of abnormal coronary arteries.

View details for DOI 10.1007/s00117-003-1005-5

View details for Web of Science ID 000220244800002

View details for PubMedID 14991130

Abstract

Nowadays coronary artery bypass grafting is increasingly performed using arterial grafts. Purpose of the study was the evaluation of a appropriate 16 detector-row CT angiography protocol in patients after predominantly arterial bypass grafting. Fourteen patients after bypass grafting were including into the study and CT angiography carried out in the early postoperative period using a 16 detector-row CT system. To reduce cardiac pulsation artifacts data acquisition was implemented using ECG-gating algorithms. Overall 43 grafts (37 arterial, 6 venous) were examined. In 13 patients surgery had been performed using composite grafts with T or TY configuration. The mean heart rate was 74.1 bpm and showed a negative correlation to the image quality (r=-0.65; p=0.01). However, all data sets were diagnostic. Contrast injection protocol allowed for a homogeneous opacification throughout the vessels of interest. All non-delineationable grafts (5) showed a close proximity to the heart (T or Y grafts). Cardiac surgery is increasingly focusing on arterial revascularisation in bypass grafting and therefore leading to new demands for non-invasive bypass graft imaging. 16 detector-row CT allows a reliable visualization of even composite arterial grafts. However, for detection of grafts in the proximity of the heart a reduction of the heart rate (<65-70) still seems to be necessary.

View details for PubMedID 14991132

Abstract

Electron beam tomography (EBT) directly competes with other non-invasive imaging modalities, such as multislice computed tomography, magnetic resonance imaging, and echocardiography, in the diagnostic assessment of cardiac diseases. EBT is the gold standard for the detection and quantification of coronary calcium as a preclinical sign of coronary artery disease (CAD). Its standardized examination protocols and the broad experience with this method favor EBT. First results with multislice CT indicate that this new technology may be equivalent to EBT for coronary calcium studies. The principal value of CT-based coronary calcium measurements continues to be an issue of controversy amongst radiologists and cardiologists due to lack of prospective randomized trials. Coronary angiography with EBT is characterized by a high negative predictive value and, in addition, may be indicated in some patients with manifest CAD. It remains to be shown whether coronary angiography with multislice CT is reliable and accurate enough to be introduced into the routine work-up, to replace some of the many strictly diagnostic coronary catheterizations in Germany and elsewhere. Assessment of coronary stent patency with EBT is associated with several problems and in our opinion cannot be advocated as a routine procedure. EBT may be recommended for the evaluation of coronary bypasses to look for bypass occlusions and significant stenoses, which, however, can be equally well achieved with multislice CT. Quantification of myocardial perfusion with EBT could not replace MRI or other modalities in this field. EBT has proven to be accurate, reliable and in some instances equivalent to MRI, which is the gold standard for the quantitative and qualitative evaluation of cardiac function. Some disadvantages, not the least of which is the limited distribution of electron beam scanners, favor MRI for functional assessment of the heart.

View details for Web of Science ID 000188227800004

View details for PubMedID 14712404

Abstract

Since the introduction of last generation multislice MSCT systems and the development of simultaneous electrocardiographic-tracing image acquisition and retrospective reconstruction techniques into clinical routine, cardiac MSCT has been considered a very useful non-invasive technique for the study of cardiac pathology in the daily clinical practice. One of the main clinical applications of this diagnostic technique is the evaluation of the coronary arteries including detection and quantification of coronary calcium, multislice CT coronary angiography (anatomy, anatomical variants and anomalies of the origin and course), the angiographic evaluation of the patency of aortocoronary by-pass grafts and coronary stents, and plaque characterization. The new reconstruction and postprocessing programs allow to obtain, in addition, parameters of myocardial morphology and contraction and cardiac function. Other clinical applications include the characterization of cardiac masses and the evaluation of the pericardium.

View details for PubMedID 15146206

View details for Web of Science ID 000188320400007

View details for PubMedID 15015881

Abstract

The aim of this study was to quantitatively assess non-calcified coronary artery plaques and to determine their predictive value for the detection of coronary artery disease (CAD). A total of 179 patients underwent a calcium screening examination and a contrast-enhanced multidetector-row computed tomography angiography (MDCT) of the coronary arteries for various indications. The traditional calcium scores were evaluated and all examinations were reviewed for the presence of non-calcified plaques with an attenuation of 0-130 Hounsfield units (HU). The number, mean attenuation, and volume of these non-calcified plaques were recorded. All patients also underwent conventional catheter angiography. Coronary calcium was detected in 73% (131 of 179) of the patients. Overall incidence of purely non-calcified plaques was 30% (53 of 179). In 27% of the patients (48 of 179) no calcium was detected; however, 15% of these patients without calcifications showed non-calcified plaques (7 of 48). Significant correlations were found between the volume of calcified plaques, volume of non-calcified plaques, and total plaque volume. There were significant differences in plaque composition comparing different risk factor profiles and different stages of CAD. Volumetric assessment of non-calcified coronary artery plaques is feasible using contrast-enhanced MDCT. Screening for non-calcified plaques identifies patients with signs of CAD that are missed in a calcium screening examination.

View details for DOI 10.1007/s00330-003-2053-y

View details for Web of Science ID 000185980600012

View details for PubMedID 12920562

Abstract

This study was designed to determine the optimal contrast protocol for 4-detector-row computed tomography angiography of the heart.Sixty patients were randomly assigned to 1 of 4 groups with 300 and 400 mg/mL iodine concentrations and 2.5 and 3.5 mL/s flow rates. Contrast density was measured in the left ventricular cavity and coronary arteries.Low iodine concentration injected at slow flow rate (0.75 g iodine/s) resulted in acceptable contrast enhancement in only 53.8% of the patients. There was no significant difference between low contrast concentration injected at high flow rate and high contrast concentration injected at slow flow rate ( approximately 1 g iodine/s). High contrast concentration administered with high flow rates (1.4 g iodine/s) may result in an enhancement above 350 Hounsfield units (HU) and interfere with coronary calcifications.The injection of approximately 1 g iodine/s resulted in an optimal (250-300 HU) contrast enhancement for cardiac 4-detector-row computed tomography.

View details for DOI 10.1097/01.rli.0000084886.44676.e4

View details for Web of Science ID 000189030700002

View details for PubMedID 14566178

Abstract

MR and CT imaging are emerging as promising complementary imaging modalities in the primary diagnosis of CAD and for the detection of subclinical atherosclerotic disease. For the detection or exclusion of significant CAD, both cardiac CT (including coronary calcium screening and non-invasive coronary angiography), and cardiac MRI (using stress function and stress perfusion imaging) are becoming widely available for routine clinical evaluation. Their high negative predictive value, especially when combining two or more of these modalities, allows the exclusion of significant CAD with high certainty, provided that patients are selected appropriately. The primary goal of current investigations using this combined imaging approach is to reduce the number of unnecessary diagnostic coronary catheterizations, and not to replace cardiac catheterization altogether. For the diagnosis of obstructive coronary atherosclerosis and for screening for subclinical disease, CT and MRI have shown potential to directly image the atherosclerotic lesion, measure atherosclerotic burden, and characterize the plaque components. The information obtained may be used to assess progression and regression of atherosclerosis and may open new areas for diagnosis, prevention, and treatment of coronary atherosclerosis. Further clinical investigation is needed to define the technical requirements for optimal imaging, develop accurate quantitative image analysis techniques, outline criteria for image interpretation, and define the clinical indications for both MR or CT imaging. Additional studies are also needed to address the cost effectiveness of such a combined approach versus other currently available imaging modalities.

View details for PubMedID 14719573

Abstract

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document will focus on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

View details for DOI 10.1161/01.CIR.0000087481.55887.C9

View details for Web of Science ID 000185909100014

View details for PubMedID 14557340

Abstract

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

View details for DOI 10.1161/01.CIR.0000087480.94275.97

View details for Web of Science ID 000185767000003

View details for PubMedID 14530185

Abstract

Multi-detector-row CT angiography (CTA) is a new technology that allows for non-invasive investigation of coronary atherosclerosis in patients. The relation between the morphology of atherosclerotic plaques assessed by CTA and histopathology is unknown. We investigated 11 human cadaver heart specimens. A mixture of methylcellulose and CT contrast media was injected into the coronary arteries to achieve in-vivo-like contrast enhancement within the coronary artery lumen. The morphologic pattern of atherosclerotic lesions found on CTA images and the tissue attenuation of non-calcified plaques were determined. After CTA imaging, atherosclerotic lesions in the coronary arteries were macroscopically identified and characterized histopathologically according to American Heart Association criteria. A total of 50 and 40 lesions were found macroscopically and by CTA, respectively. Thirty-three lesions could have been compared directly. The sensitivity of CTA compared with macroscopic detection of atheromas, fibroatheromas, fibrocalcified, and calcified lesions was 73, 70, 86, and 100%, respectively. The mean CT attenuation of predominantly lipid-rich and fibrous-rich plaques was significantly different (47+/-9 and 104+/-28 HU, respectively; p<0.01). Atherosclerotic coronary plaques detected by CTA may represent different stages of coronary atherosclerosis. The tissue attenuation of non-calcified plaques may allow for assessment of their predominant component.

View details for DOI 10.1007/s00330-003-1889-5

View details for Web of Science ID 000185537700005

View details for PubMedID 12692681

Abstract

A 42-year-old woman was admitted because of a newly perceived pain localized in the ventral part of the fifth left rib. The physical examination was normal except for a palpable nodular thyroid and pain on palpation of this rib. The patient history contained a serious car accident and severe cigarette abuse.The chest x-ray in "bone technique" showed an osteolysis in the fifth left rib, which was confirmed by computer tomography and bone scan. The high resolution CT scan of the lung revealed a discrete interstitial reticular pattern with minor cystic alterations without lymph node enlargement.Transbronchial biopsy, bronchoalveolar lavage and a malignancy screening did not lead to a diagnosis. Therefore, the patient was submitted to partial rib resection and open lung biopsy. Histological examination revealed a Langerhans cell histiocytosis. The initial therapeutic approach was a strict smoking cessation.The differential diagnosis of a lytic bone lesion in a heavy smoker should include Langerhans cell histiocytosis. On smoking cessation a remission of the disease may be achieved.

View details for Web of Science ID 000184830500003

View details for PubMedID 12920667

Abstract

The development of multi-detector-row CT (MDCT), within recent years, dramatically improved image quality and expanded the applications for non-invasive CT angiography. Since the introduction of four-detector-row CT (4-DCT) systems in 1998, MDCT technology has spread rapidly and is now widely available. This technique already meets the requirements for many vascular applications with respect to acquisition speed, anatomical coverage and spatial resolution. The newest MDCT scanners offer the advantages of up to 16 detector rows and gantry rotation as fast as 500 msec, further expanding the possibilities for CT angiography. For the assessment of the aorta and the iliac vessels MDCT has already proven to be superior to single detector CT and comparable to conventional angiography. This article reviews the status of MDCT angiography, including technical aspects, reformation methods and limitations, and clinical applications at the current state of the art.

View details for DOI 10.1053/sult.2003.S0887-2171(03)00051-9

View details for Web of Science ID 000184815700007

View details for PubMedID 12954008

Abstract

The aim of this study was to reduce radiation exposure in multislice CT (MSCT) coronary artery calcium screening using different tube settings, and to determinate its impact on the detection and quantification of coronary artery calcification. Forty-eight patients underwent routine MSCT coronary artery calcium scoring (Somatom VolumeZoom, Siemens, Forchheim, Germany) with retrospective ECG-gated data acquisition. Scanning was performed with a 4 x 2.5-mm collimation. In each patient data acquisition was performed twice using tube settings of 120 kVp with 133 mAs (protocol 1) and of 80 kVp with 300 mAs (protocol 2). Together with the 80-kVp protocol additional online ECG-related tube current modulation (ECG pulsing) was used. Three-millimeter overlapping slices (increment 1.5 mm) were calculated for each data set. Semi-automated calcium quantification was performed calculating absolute Ca-hydroxylapatite mass. In addition to patient examinations, the radiation exposure for both protocols was evaluated using computed tomography dose index (CTDI) phantom measurements. Protocol 2 showed a significantly lower patient radiation exposure than protocol 1 (0.72 vs 2.04 mSv; p<0.0001). The CTDI phantom measurements revealed a 65% reduction of radiation dose. Calcium scoring results of both protocols showed a high correlation ( r=0.99; p<0.0001) for absolute Ca-Hydroxylapatite mass measurements. Using 80-kVp protocols patient radiation exposure can be significantly reduced in MSCT coronary artery calcium screening without affecting the detection and quantification of coronary artery calcification; therefore, this technique should be used with retrospective ECG-gated cardiac CT examinations in patients with regular sinus rhythm.

View details for DOI 10.1007/s00330-003-1895-7

View details for Web of Science ID 000184755800021

View details for PubMedID 12759771

Abstract

The introduction of multislice CT into clinical radiology constitutes a quantum leap that significantly widens the scope of vascular CT imaging. The advances over conventional spiral CT have been quantitative, mainly in terms of increased image acquisition speed which provides unprecedented volume coverage and spatial resolution. Moreover, significant technical innovations, such as cardiac scanning capabilities, have brought about a qualitative shift towards applications that were thought to be beyond the scope of CT imaging. This way multislice CT offers a wealth of new opportunities for quickly and accurately diagnosing suspected vascular disease in all organ systems; however, as we move towards faster and faster image acquisition techniques, we are also facing new challenges that require development of novel strategies in order to take full advantage of the increased capabilities of multislice CT in its current form and future generations of CT scanners.

View details for DOI 10.1007/s00330-003-1842-7

View details for Web of Science ID 000184755800024

View details for PubMedID 12942298

Abstract

Electron beam computed tomography (EBCT) and multislice computed tomography (MSCT) are both suitable for non-invasive identification of coronary stenoses.To compare intravenous coronary EBCT angiography (EBCTA) and MSCT angiography (MSCTA) with regard to image quality and diagnostic accuracy.EBCTA was done using an Imatron C-150 XP scanner in 101 patients following a standard protocol (slice thickness 3 mm, overlap 1 mm, acquisition time 100 ms, prospective ECG trigger). For MSCTA in a different set of 91 patients (using a Siemens Somatom Plus4VZ scanner), the whole volume of the heart was covered in a spiral technique by four simultaneous detector rows. Using retrospective ECG gating, the raw data were reconstructed in (mean (SD)) 215 (12) axial slices acquired in diastole (slice thickness 1.25 mm, overlap 0.5 mm, acquisition time 250 ms/slice).With EBCTA, 76% of predetermined coronary segments in a nine segment model could be assessed with diagnostic image quality, and with MSCTA, 82%. A low contrast to noise ratio with EBCTA, and the presence of motion artefacts with MSCTA were the main reasons for inadequate image quality. Using conventional angiography as the gold standard, 77% of stenoses of > 50% could be identified correctly with EBCTA and 82% with MSCTA. Significant stenoses were correctly ruled out in 93% of segments with EBCTA, and in 96% of segments with MSCTA. The average contrast to noise ratio was higher with MSCTA than with EBCTA (9.4 v 6.5; p < 0.001).EBCTA and MSCTA show similarly high levels of accuracy for determining and ruling out significant coronary artery stenoses. MSCTA is capable of providing good image quality in more coronary segments than EBCTA because of its better contrast to noise ratio and higher spatial resolution. Motion artefacts seen at heart rates of > 75 beats/min and a higher radiation exposure are the main limitations of MSCTA.

View details for Web of Science ID 000182853600013

View details for PubMedID 12748218

Abstract

Despite worldwide efforts aimed at primary and secondary prevention, heart disease is still the leading cause of death in the western world. There is great interest in developing tools for noninvasive assessment of the presence and degree of coronary artery disease. The advent of multidetector-row CT allows high-resolution volume coverage of the entire thorax and motion-free imaging of the heart and adjacent vessels within one breathhold. An exciting application with significant potential for cardiac risk stratification, which may overcome the obvious limitations of coronary calcium imaging in the future, is the use of the cross-sectional nature of contrast-enhanced multidetector-row CT coronary angiography for assessment of total coronary artery plaque burden.

View details for DOI 10.1016/S0033-8389(03)00033-2

View details for Web of Science ID 000182933500004

View details for PubMedID 12797602

View details for DOI 10.1053/sroe.2003.50013

View details for Web of Science ID 000183560600005

View details for PubMedID 12854437

View details for DOI 10.1016/S0002-9149(02)03411-2

View details for Web of Science ID 000181574800013

View details for PubMedID 12633805

Abstract

The newest generation multi-detector-row CT scanner is allowed for investigation of the entire heart within a breathhold period of approximately 20 s. Within this time 250 slices with a thickness of 1 mm each are acquired. In conjunction with the ECG signal the images are acquired with a temporal resolution of 210 ms in the mid diastolic phase of the heart.In patients with a heart rate < 60 beats per minute images free of motion artefacts can be reconstructed, that allow for assessment of the coronary artery lumen as well as calcified and non-calcified lesions in the coronary artery wall. Such lesions may be differentiated into thrombus, atheroma and fibrocalcified plaques on the base of characteristic morphologic criteria.The absence of coronary artery lesions in symptomatic patients with atypical chest pain allows for reliable exclusion for coronary heart disease. In asymptomatic patients with cardiovascular risk factors we first perform an investigation without contrast media to detect coronary calcifications as a marker of atherosclerosis. To assess the complete extent of coronary atherosclerosis in high risk patients, we then consider a contrast enhanced CT study.

View details for DOI 10.1007/s00059-003-2449-0

View details for Web of Science ID 000181382300004

View details for PubMedID 12616318

View details for PubMedID 12627782

Abstract

Selective coronary angiography (SCA) is the standard invasive procedure for diagnosis in patients eligible for coronary artery bypass grafting (CABG). A recently developed, highly sensitive multidetector computed tomography (MDCT) scan holds promise to be of almost comparable quality and predictiveness. We examined a blinded series of preoperative patients who were admitted to hospital for conventional and minimally invasive CABG procedures. Patients underwent CT scans in addition to SCA; findings were compared regarding location and degree of coronary artery stenosis.Twenty patients underwent electrocardiogram-gated helical CT scanning. Images with 250 ms effective exposure time were reconstructed with retrospective electrocardiogram gating. Location and degree of coronary stenoses were described and compared with findings of SCA. The study was limited to patients with a heart rate of less than 70 beats per minute and who had the ability to hold their breath for 20 to 30 seconds.Coronary arteries were clearly displayed by MDCT. Compared with SCA, sensitivity was 92%, specificity 84%, and negative predicted value 89% for significant stenosis (more than 50%). Early forms of atherosclerotic changes were even clearer on MDCT. In addition, the CT examination allowed differentiation of calcified and fatty or fibrous stenoses.Multidetector CT scanning is an effective noninvasive technique for the diagnosis of coronary artery disease. In selected patients, MDCT scanning might be able to replace SCA as a preoperative test for CABG procedures. The intrathoracic situs can be clearly exposed as it is important for the planning of minimally invasive CABG procedures.

View details for Web of Science ID 000178452500115

View details for PubMedID 12400825

Abstract

To evaluate image quality of coronary CT angiography with retrospectively ECG-gated 16 multi-slice spiral CT (MSCT), reconstructed with 0.75 mm slice thickness for optimal spatial resolution and with 1.3 mm slice thickness, to produce spatial resolution comparable to a 4-MSCT.Ten patients underwent coronary CT angiography with a 16-MSCT (Siemens Sensation 16, Forchheim, Germany) with 0.75 mm detector collimation. Raw helical CT data were retrospectively reconstructed using two different settings. Setting A: B20f smooth kernel, axial MPR with 1.3 mm slice thickness and 0.7 mm increment. Setting B: B35f "HeartView" medium-smooth kernel, 0.75 mm slice thickness, 0.5 mm increment. In the axial slices two regions of interest (ROIs) were placed in the area of the aortic root (AR) and more caudal in the area of the left ventricle (LV). Image noise was determined by the standard deviation of the CT numbers.Two readers determined visibility of coronary arteries by standardized maximum intensity projections (MIP) post-processing in left, right anterior and left anterior oblique projection plane from setting A and B. Each projection was rated on a five point rating scale concerning plaque delineation. Points determined for each data set were summed up and used for comparison.No significant difference between the CT-numbers was found for setting A and B (A: 283.0 in AR/295.9 in LV and B: 282,9 in AR/297.2 in LV; p >0.2). However, the image noise was significantly different for setting A and B (A: 4.46 in AR/1.67 in LV and B: 8.16 in AR/7.38 in LV; p <0.01). Better delineation of the coronary arteries and atherosclerotic lesions could be achieved from MIP projections in setting B compared to setting A.Higher image noise is present in coronary 16-MSCT with thin-slice reconstruction compared to simulated 4-MSCT. However the MIP-reconstructions benefit most from the higher spatial resolution.

View details for DOI 10.1007/s00117-002-0787-1

View details for Web of Science ID 000178406900007

View details for PubMedID 12244475

Abstract

The authors compared multislice CT angiography and selective angiography for the assessment of coronary artery disease.In 28 patients, the presence and degree of coronary artery stenoses were determined in coronary segments prepared with beta-blocker for good image quality with multislice CT.In 187 coronary artery segments, sensitivity, specificity, and negative predictive value for the detection of stenoses >50% with multislice CT angiography were 81%, 90%, and 97%, respectively. The agreement for determining the degree of stenoses with multislice CT angiography and selective coronary angiography was only moderate (kappa = 0.58).Because of the limited spatial resolution, it is not possible with multislice CT angiography to determine the degree the coronary artery stenoses precisely. However, the high negative predictive value indicates that multislice CT may be a suitable tool to reliably rule out coronary artery disease.

View details for Web of Science ID 000179478200015

View details for PubMedID 12439310

View details for PubMedID 12390013

Abstract

Electron-beam Computed Tomography (EBCT) has been used for years to quantify coronary artery calcification as a marker of coronary atherosclerosis. The aim of this study was to determine the diagnostic accuracy of a new scanner, the Multi-slice Spiral CT (MSCT), for the assessment of coronary calcification and to compare this new technique to EBCT. The study population consisted of 99 male patients, aged 60 +/- 10 years with suspected or known coronary artery disease. With EBCT 40 axial slices, ECG-triggered (scan time = 100 ms, slice thickness = 3 mm), were acquired in one breath-hold (35 +/- 5 s). For MSCT simultaneous acquisition of four axial slices (scan time = 250 ms, slice thickness = 2.5 mm), allowed the entire heart (48 slices) to be covered in one breath-hold of 25 +/- 5 s. For quantification of coronary calcium the Volumetric Calcium Score (VCS) was calculated. There was an excellent correlation for the VCS (r = 0.994, p = 0.01, mean difference = 97 +/- 115) between both scanners. Comparison of low (1-100), moderate (101-400), high (401-1000) and very high score values (>1,000) showed no significant differences. The number of calcified lesions and densities were statistically not different. Mean variability of the two scans was 17%. The MSCT scanner is equivalent to EBCT for the determination and quantification of coronary calcium and can therefore be used for calcium screening. With application of the spiral mode technique further improvement in variability can be expected, thus allowing for follow-up studies to determine progression or regression of atherosclerosis with high accuracy.

View details for Web of Science ID 000176584100009

View details for PubMedID 12123323

Abstract

The aim of this study was to compare contrast-enhanced electron-beam computed tomography (EBCT) and navigator-echo-based MRI of the coronary arteries in the same patient population. Both methods were assessed for visualization of the coronary arteries and their diagnostic accuracy in identifying significant coronary artery stenoses compared with conventional coronary angiography. Twenty patients with known coronary artery disease were examined with both contrast-enhanced EBCT and a respiratory-gated MRI sequence. A grading system was used to evaluate the image quality. Sensitivity and specificity for the detection of significant coronary artery stenoses was evaluated compared with conventional coronary angiography. With EBCT, 89% of the main coronary arteries could be completely visualised in the proximal and middle segments; with MRI, 83% were visualised. With EBCT the sensitivities for identifying significant (>/=50%) stenoses in proximal and middle vessel segments were 75% in the main stem, 88% in the left anterior descending coronary artery, 75% in the left circumflex coronary artery, and 90% in the right coronary artery. Respective sensitivities for MRI angiograms were 75, 82, 75 and 80%. With both modalities a sufficient image quality of the main coronary arteries can be obtained in most cases. The diagnostic capability for detecting significant stenoses is comparable for both methods.

View details for DOI 10.1007/s00330-002-1320-7

View details for Web of Science ID 000177003700006

View details for PubMedID 12111056

Abstract

This article is designed to provide the reader information about the technical details of retrospective ECG-gated spiral 4SCT and its applications for the detection and quantification of coronary artery calcification, the detection of coronary artery stenoses, and the characterization of coronary atherosclerotic plaques.

View details for Web of Science ID 000177204900007

View details for PubMedID 12171184

Abstract

A method for cardio-thoracic multislice spiral CT imaging with ECG gating for suppression of heart pulsation artifacts is introduced. The proposed technique offers extended volume coverage compared with standard ECG-gated spiral scan and reconstruction approaches for cardiac applications: Thin-slice data of the entire thorax can be acquired within one breath-hold period using a four-slice CT system. The extended volume coverage is enabled by a modified approach for ECG-gated image reconstruction. For a CT system with 0.5-s gantry rotation time, images are reconstructed with 250-ms image temporal resolution. Instead of selecting scan data acquired in exactly the same phase of the cardiac cycle for each image as in standard ECG-gated reconstruction techniques, the patient's ECG signal is used to omit scan data acquired during the systolic phase of highest cardiac motion. With this approach cardiac pulsation artifacts in CT studies of the aorta, of paracardiac lung segments, and of coronary bypass grafts can be effectively reduced.

View details for DOI 10.1007/s00330-002-1388-0

View details for Web of Science ID 000176197400033

View details for PubMedID 12042960

Abstract

High reproducibility is a key requirement for coronary calcium scoring in follow-up examinations. We investigated the inter-examination reproducibility of calcium scoring with retrospectively ECG-gated multisection spiral CT (MSCT). Fifty patients were examined twice with MSCT. Slices were reconstructed with retrospective ECG gating in the diastolic phase with 3-mm slice width and up to 125-ms temporal resolution. We calculated the Agatston score, calcium volume with and without isotropic interpolation, and calcium mass, and derived the mean and median variability. We investigated the change of variability with use of 3-mm non-overlapping and overlapping increments (2, 1.5, 1 mm). Use of overlapping increment results in considerably reduced interscan variability. We observed a minimum mean variability of 12% and a minimum median variability of 9% for the Agatston score. For volume and mass quantification we obtained a minimum mean variability of 7.5% and a minimum median variability of 5%. Multisection spiral CT enables coronary calcium quantification with high reproducibility in follow-up examinations mainly founded on image data with reduced partial-volume errors due to overlapping increment.

View details for DOI 10.1007/s00330-002-1394-2

View details for Web of Science ID 000176197400037

View details for PubMedID 12042964

Abstract

The purpose of the study was to evaluate feasibility and safety of CT-fluoroscopy in the drainage of pericardial effusion in cases not accessible by sonography.Eleven drainages were performed in Seldinger-technique under CT-fluoroscopy on eight patients suffering from pericardial effusion. The inclusion criterion was a sonographically proved pericardial effusion not drainable under sonographic surveillance. In seven procedures the catheter was positioned using a medial, in four procedures a lateral approach from the apex was chosen.All catheters could be placed successfully (11/11) in the pericardial effusion and allowed for draining of the effusion in 10 of 11 cases. One epicardial laceration necessitated a surgical approach. The elapsed total procedure time for the drainage was on average 18:23 +/- 8:58 minutes.Visual surveillance by CT-fluoroscopy is a feasible method in the drainage of pericardial effusions even in cases not accessible by ultrasound.

View details for Web of Science ID 000175913000004

View details for PubMedID 12021589

Abstract

Our objective was to evaluate image quality and radiation exposure of retrospectively ECG-gated multislice helical CT (MSCT) investigations of the heart with ECG-controlled tube current modulation. One hundred patients underwent MSCT scanning (Somatom VolumeZoom, Siemens, Forchheim, Germany) for detection of coronary artery calcifications. A continuous helical data set of the heart was acquired in 50 patients (group 1) using the standard protocol with constant tube current, and in 50 patients (group 2) using an alternative protocol with reduced radiation exposure during the systolic phase. The standard deviations (SD) of predefined regions of interest (ROIs) were determined as a measure of image noise and were tested for significant differences. There was no significant difference between group 1 and group 2 with respect to image noise. Radiation exposure with and without tube current modulation was 1.0 and 1.9 mSv ( p<0.0001), respectively, for males and 1.4 and 2.5 mSv ( p<0.0001), respectively, for females; thus, there was a mean dose reduction of 48% for males and 45% for females, respectively. The ECG-controlled tube current modulation allows significant dose reduction when performing retrospectively ECG-gated MSCT of the heart.

View details for DOI 10.1007/s00330-001-1278-x

View details for Web of Science ID 000175613700011

View details for PubMedID 11976849

Abstract

(a) To determine the accuracy of multi-detector row computed tomography (CT) in the measurement of the calcium concentration in a cardiac CT calibration phantom and (b) to assess the correlation of a traditional 3-mm section width CT coronary screening protocol and a 1.25-mm section width CT angiography imaging protocol in the quantification of the absolute mass of coronary calcium in patients who underwent both coronary screening and CT angiography with a multi-detector row CT scanner.A heart phantom containing calcified cylinders was scanned to determine calibration factors and absolute calcium mass. In 50 patients, the variability (value 1 - value 2/mean value 1 - value 2), limit of agreement (+/-2SD value 1 - value 2), and systematic error (mean value 1 - value 2) of the total amount of coronary calcium calculated at traditional 3-mm section width CT and at 1.25-mm section width CT angiography were determined.The correlation coefficient between the 3-mm section width, nonenhanced protocol and the 1.25-mm section width CT angiography protocol was very high (r = 0.977) and the mean variability was low (19.7%) for the absolute mass. There was a systematic error of -6.7 mg and a limit of agreement between 45.0 mg and -58.5 mg.Use of the mass quantification algorithm in combination with a calibration phantom allows accurate quantification of coronary calcium. Measurements of calcium mass obtained at 1.25-mm section width CT angiography have the best agreement with those obtained at the traditional 3-mm section width imaging protocol.

View details for DOI 10.1148/radio.223010909

View details for Web of Science ID 000175270000028

View details for PubMedID 11997555

Abstract

The distribution of mineralization of the subchondral bone plate (DMSB) is used as a parameter for the individual stress distribution of joints. In this study the DMSB of the glenoid from healthy glenohumeral joints was analyzed. In a standardized manner, 44 macroscopically normal shoulder specimens (28 individuals aged 18 to 96 years) were selected and DMSB of the glenoid was evaluated by computed tomography osteoabsorptiometry. The mineralization patterns were described, and the 2 most frequent maxima of density were localized and statistically assessed to analyze any influence of age, side, or shape of the glenoid on DMSB. An anterior-superior maximum was found in 100% and a posterior maximum in 82%. Three different patterns of DMSB were distinguished in relation to the constant anterior-superior maximum: 68% were not combined with a further central or anterior-inferior maximum (type A), whereas a central maximum coexisted in 18% (type B) and an anterior-inferior maximum in 14% (type C). The localization of the anterior-superior and posterior maxima was independent of age or side of the glenoid, indicating a constant long-term stress distribution in healthy glenohumeral joints. The typical localization of the density maxima showed that stress distribution is usually peripherical (82%) and often bicentric. Functional aspects related to internal rotation of the arm support a more constant anterior than posterior stress on the glenoid surface.

View details for DOI 10.1067/mse.2002.121635

View details for Web of Science ID 000175664200012

View details for PubMedID 11988730

Abstract

To compare different reconstruction thicknesses of thin-collimation multi-detector row spiral computed tomographic (CT) data sets of the chest for the detection of subsegmental pulmonary emboli.A multi-detector row spiral CT protocol for the diagnosis of pulmonary embolism was used that consisted of scanning the entire chest with 1-mm collimation within one breath hold. In 17 patients with central pulmonary embolism, the raw data were used to perform reconstructions with 1-mm, 2-mm, and 3-mm section thicknesses. For each set of images, each subsegmental artery was independently graded by three radiologists as open, containing emboli, or indeterminate.For the rate of detection of emboli in subsegmental pulmonary arteries, use of the 1-mm section width yielded an average increase of 40% when compared with the use of 3-mm-thick sections (P <.001) and of 14% when compared with the use of 2-mm-thick sections (P =.001). With the use of 1-mm sections versus 3-mm sections, the number of indeterminate cases decreased by 70% (P =.001). Interrater agreement was substantially better with the use of 1-mm and 2-mm sections than with the use of 3-mm sections.For the diagnosis of subsegmental pulmonary emboli at multi-detector row CT, the use of 1-mm section widths results in substantially higher detection rates and greater agreement between different readers than the use of thicker sections.

View details for Web of Science ID 000173502500028

View details for PubMedID 11818617

View details for Web of Science ID 000172412300022

View details for PubMedID 11703970

Abstract

To evaluate the effectiveness of electrocardiographically (ECG)-gated retrospective image reconstruction for multi-detector row computed tomographic (CT) coronary angiography in reducing cardiac motion artifacts and to evaluate the influence of heart rate on cardiac image quality.Sixty-five patients with different heart rates underwent coronary CT angiography. Raw helical CT data and ECG tracings were combined to retrospectively reconstruct at the defined consecutive z position with a temporal resolution of 250 msec per section. The starting points of the reconstruction were chosen between 30% and 80% of the R-R intervals. The relationships between heart rate, trigger delay, and image quality were analyzed.Optimal image quality was achieved with a 50% trigger delay for the right coronary artery and 60% for the left circumflex coronary artery. Optimal image quality for the left anterior descending coronary artery was equally obtained at 50% and 60% triggering. A significant negative correlation was observed between heart rate and image quality (P <.05). The best image quality was achieved when the heart rate was less than 74.5 beats per minute.To achieve high image quality, the heart rate should be sufficiently slow. Selection of appropriate trigger delays and a decreasing heart rate are effective to reduce cardiac motion artifacts.

View details for Web of Science ID 000170616700023

View details for PubMedID 11526271

Abstract

The aim of this study was to investigate the reliability of calcium scoring (CS) and electron beam computed tomographic angiography (EBCTA) as a noninvasive tool in the diagnosis of coronary artery disease (CAD): 93 consecutive patients (aged 59 +/- 9 years) with symptoms suspicious for CAD underwent CS. In 87 of these subjects, an additional EBCTA investigation was performed. Using receiver-operating characteristic curve analysis, we determined a calcium score cut point providing an overall sensitivity of 80% and a specificity of 72% in detecting patients with CAD. For clinical purposes the use of cut points is difficult. We therefore determined score ranges providing >80% specificity (high score range) and >85% sensitivity (low score range) and determined the scores between these ranges as equivocal borderline scores. Calculated on a per-segment basis in assessable proximal and midcoronary segments, the sensitivity for detecting coronary stenoses >50% was 78%, and the specificity was 93%. Thus, 32 of 44 patients with significant CAD and 24 of 49 patients without CAD were correctly classified. The combination of CS and EBCTA predicted CAD in 77% (72 of 93) of patients. No or low calcium scores provided high specificity for ruling out CAD. The addition of EBCTA in those patients improved sensitivity. In patients with high calcium scores, accuracy of EBCTA was not significantly different from CS alone (72% vs 83%), whereas in patients with borderline scores it was significantly superior (80% vs 58%, p <0.03). Thus, the complementary use of CS and EBCTA appears beneficial, particularly in patients with borderline scores, and could improve sensitivity in the low score range. In the presence of high scores, no major diagnostic gain from an additional EBCTA versus CS alone could be observed.

View details for Web of Science ID 000170090500004

View details for PubMedID 11472697

Abstract

We tested breath-held 1-mm multislice helical CT for obtaining both contiguous and high-resolution CT sections of the chest from a single set of raw data.Seventy patients with suspected focal and diffuse lung disease were allocated into two groups for comparison. The first group (n = 35) underwent multislice helical CT of the chest with 1-mm collimation and a pitch of 6. From the raw data, 5-mm contiguous and 1.25-mm high-resolution CT sections were reconstructed. The second group (n = 35) underwent conventional single-slice helical CT and high-resolution CT. High-resolution CT sections and 5-mm scans were rated for overall image quality, spatial resolution, subjective signal-to-noise ratio, diagnostic value, depiction of bronchi and parenchyma, and motion and streak artifacts. The 5-mm scans were also rated for contrast resolution and depiction of the heart and vessels. Radiation dose was calculated.We rated 5-mm multislice helical CT superior to 5-mm single-slice helical CT, having a significantly higher total score (p = 0.0001). No significant difference (p = 0.986) was found between multislice and single-slice high-resolution CT sections. Radiation dose was 5.55 mSv for multislice helical CT and 5.50 mSv for single-slice helical CT.Contiguous chest scans of superior quality and high-resolution CT sections of equal image quality compared with single-slice helical CT can be obtained using multislice helical CT. Therefore, a comprehensive diagnosis is feasible in patients with suspected focal and diffuse lung disease by obtaining a single scan.

View details for Web of Science ID 000169457900035

View details for PubMedID 11418423

Abstract

Detection of coronary artery calcifications with slice by slice prospective ECG triggering is feasible with electron beam CT as well as with single and multi-row-detector CT (MDCT). The radiation exposure to the patient to obtain comparable image quality is similar for all three modalities utilizing this prospective acquisition technique. Alternatively, coronary screening can be performed by MDCT with retrospective EKG spiral gating. Radiation exposure to the patient with this technique is significantly higher than with prospective triggering. Nevertheless, acquisition of the entire volume of the heart with retrospective gating holds promise to improve reproducibility of coronary calcium measurements, especially in patients with a low amount of coronary calcium and in patients with atrial fibrillation. If retrospective gating is used for CT angiography (CTA) with MDCT this allows to use thin slices (1.25 mm) and to perform the acquisition within one breath hold period (app. 35 s). This technique is currently limited by the temporal resolution per slice (250 ms). In order to achieve diagnostic image quality the heart rate of the patient thus needs to be sufficiently low. Therefore, in cases with heart rates significantly higher than 70 beats/min betablocker have to be administered for patient preparation as long as there are no contraindications for such a regimen. Because of low image noise and high spatial resolution CTA with MDCT is able to display the entire extent of atherosclerosis allowing to visualize calcified as well as non-calcified plaques of the coronary arteries. Under clinical conditions CTA has the potential to accurately rule out or diagnose significant coronary stenoses of the proximal and mid-segments of the coronary artery tree when compared to conventional selective coronary angiography.

View details for Web of Science ID 000170286700006

View details for PubMedID 11587454

Abstract

The purpose of our study was to establish the most suitable algorithm to compare coronary artery calcium measurements performed with electron beam CT and multirow detector CT for the assessment of coronary artery disease.Coronary artery screening was performed in 100 patients with both electron beam and multirow detector CT. The images were transferred to a dedicated workstation for determination of the calcium score, volume, mass, density, and number of lesions. In addition to the traditional threshold of 130 H, the score of multirow detector CT studies was reevaluated at a threshold of 90 H. Fifty-nine of the patients underwent conventional coronary catheterization. Receiver operating characteristic curve analysis of the different scoring algorithms for detection of significant coronary artery stenosis was performed.The correlation between electron beam CT and multirow detector CT was high for every quantification algorithm. Determination of the score and the number of lesions with multirow detector CT revealed a systematic error of the measurement compared with electron beam CT. The areas under the curve in the receiver operating characteristic curve analyses for electron beam and multirow detector CT were similar for the score, volume, and mass, whereas they were lower for the density. No significant difference was found for the areas under the curve between scores using a 130-H and those using a 90-H threshold.Volume and mass indexes are superior to the traditional score, density, and number of lesions for comparing the results of electron beam and multirow detector CT and for determining significant coronary artery disease.

View details for Web of Science ID 000168208900035

View details for PubMedID 11312197

Abstract

This study correlated the electron beam computed tomographic (EBCT) calcium scores with the results of coronary angiography in symptomatic patients in order to assess its value to predict or exclude significant coronary artery disease (CAD).Electron beam computed tomography is a sensitive method to detect coronary calcium. However, it is unclear whether it may play a role as a filter before invasive procedures in symptomatic patients.A total of 1,764 patients (1,225 men and 539 women) with suspected CAD from a single center were included in our study. All patients underwent calcium screening with EBCT (C150XP Imatron) and conventional coronary angiography.Fifty-six percent of men and 47% of women revealed significant coronary stenoses (> or =50%). Total exclusion of coronary calcium (14% of the study group) was associated with an extremely low probability of stenosis (<1%). With calcium scores > or =20th, > or =100th or > or =75th percentile of age groups, the sensitivity to detect stenoses decreased to 97%, 93% and 81%, respectively, in men and to 98%, 82% and 76%, respectively, in women. At the same time, the specificity increased up to 77% in men and women. There was a significant difference in coronary calcium between men and women in all age groups; however, receiver-operating characteristic curves indicated that the test can be performed with equal accuracy in all of these subgroups.Calcium screening with EBCT is a highly sensitive and moderately specific test to predict stenotic disease. Exclusion of coronary calcium defines a substantial subgroup of patients, albeit symptomatic, with a very low probability of significant stenoses.

View details for Web of Science ID 000166847200014

View details for PubMedID 11216962

Abstract

Recent promising trials that use low-dose CT for the early detection of lung cancer have reinvigorated the interest in screening approaches. At the same time the development of fast image acquisition techniques, such as multislice CT, have sparked renewed interest in cardiac imaging within the radiological community. In addition to special cardiac capabilities, multislice CT has several other features such as high acquisition speed and low-dose requirements that may make this modality a universal radiological screening tool. Non-invasive disease detection is the radiologist's domain. In this paper we identify criteria for effective screening and apply these criteria to screening approaches with multislice CT when used for detection of three disease entities: colon cancer; lung cancer; and cardiovascular disease.

View details for Web of Science ID 000171479700015

View details for PubMedID 11702131

Abstract

In recent years CT has been established as the method of choice for the diagnosis of central pulmonary embolism (PE) to the level of the segmental arteries. The key advantage of CT over competing modalities is the reliable detection of relevant alternative or additional disease causing the patient's symptoms. Although the clinical relevance of isolated peripheral emboli remains unclear, the alleged poor sensitivity of CT for the detection of such small clots has to date prevented the acceptance of CT as the gold standard for diagnosing PE. With the advent of multislice CT we can now cover the entire chest of a patient with 1-mm slices within one breath-hold. In comparison with thicker sections, the detection rate of subsegmental emboli can be significantly increased with 1-mm slices. In addition, the interobserver correlation which can be achieved with 1-mm sections by far exceeds the reproducibility of competing modalities. Meanwhile use of multislice CT for a combined diagnosis of PE and deep venous thrombosis with the same modality appears to be clinically accepted. In the vast majority of patients who receive a combined thoracic and venous multislice CT examination the scan either confirms the suspected diagnosis or reveals relevant alternative or additional disease. The therapeutic regimen is usually chosen based on the functional effect of embolic vascular occlusion. With the advent of fast CT scanning techniques, also functional parameters of lung perfusion can be non-invasively assessed by CT imaging. These advantages let multislice CT appear as an attractive modality for a non-invasive, fast, accurate, and comprehensive diagnosis of PE, its causes, effects, and differential diagnoses.

View details for Web of Science ID 000172277300023

View details for PubMedID 11702173

Abstract

To comprehensively assess thoracic anatomy and pulmonary microcirculation in pulmonary embolism by using computed tomographic (CT) angiography of the pulmonary arteries combined with functional CT imaging of blood flow.Twenty-two patients suspected of having acute pulmonary embolism underwent contrast material-enhanced thin-section electron-beam CT angiography of the pulmonary arteries. In addition, in each patient, a dynamic multisection blood flow CT study was performed on a 7.6-cm lung volume with electrocardiographic gating. Pulmonary blood flow was calculated, and perfusion parameters were visualized on color-coded maps. The color-coded maps and CT angiograms were independently evaluated, segment by segment, by two readers for perfusion deficits and the presence of clots, respectively. The results were compared.Mean pulmonary blood flow was 0.63 mL/min/mL in the occluded segments versus 2.27 mL/min/mL in the nonoccluded segments (P: =.001). The sensitivity and specificity of perfusion maps for the presence of segmental pulmonary embolism compared with those of CT angiography were 75.4% and 82.3%, respectively, with positive and negative predictive values of 79.6% and 84.7%, respectively. The false-negative findings were caused mainly by partial occlusion of vessels. In eight patients, a substantial alternative or additional pathologic entity was diagnosed.By combining CT angiography and dynamic CT imaging, a comprehensive and noninvasive diagnosis of thoracic structure and function is feasible with a single modality.

View details for Web of Science ID 000165495300011

View details for PubMedID 11110930

Abstract

Multidector-row CT (MDCT) with retrospective ECG gating allows scanning the entire heart with 1.25 mm slice thickness and 250 ms effective exposure time within 35 s investigation time. The resulting images allow for an accurate high-resolution assessment of morphological detail of both the coronary arteries and the cardiac chambers. Performing a contrast-enhanced MDCT angiography (MD-CTA) in addition to a non-enhanced scan for the detection and quantification of coronary calcifications may be indicated in patients with atypical chest pain and in young patients with high cardiovascular risk. This group of patients may show non-calcified plaques as the first sign of their coronary artery disease. As the proximal part of the coronary arteries is well displayed by MD-CTA it also helps to delineate the course in anomalous coronary vessels. Additional information is drawn from the preoperative use of MD-CTA do determine the distance of the left internal mammarian artery to the left anterior descending coronary artery prior to minimal invasive bypass grafting. Additional indications for MD-CTA are the non-invasive follow up after venous bypass grafting, PTCA, and coronary stent interventions. MD-CTA allows following the course of the coronary vessels to the level of third generation coronary segmental arteries. A definite diagonis to rule out coronary artery disease can be reliably made in vessels with a diameter of 1.5 mm or greater. With MDCT a number of different atherosclerotic changes can be observed in diseased coronary arteries. Non-stenotic lesions may show tiny calcifications surrounded by large areas of irregularly distributed soft tissue. Calcifications in this type of atherosclerotic coronary artery wall changes appear as 'the tip of iceberg'. Heavy calcifications usually tend to be non-stenotic because of vessel remodelling resulting in a widening of the coronary vessel lumen. Therefore, heavy calcifications appear to ack like an 'internal stent' for a coronary vessel segment. Humps of soft tissue either with or without calcifications are more likely to cause significant coronary artery disease and correlate with stenoses of >50% on selective coronary catheter. These humps consist of well-defined soft tissue in the coronary artery wall. The density of this soft tissue may vary between 30-70 HU. In cases where a coronary vessel is occluded by thrombotic material, a typical sign is found with enlargement of the coronary vessel, a hypodense center and a hyperdense rim. Vessel occlusion without thrombus may also appear within a collapsed and dense lumen. In addition to the investigation of the coronary arteries, CTA with MDCT is well suited to assess the presence and morphology of myocardial scars and aneurysms, intracardial tumors and thrombi.

View details for Web of Science ID 000165764000006

View details for PubMedID 11116173

Abstract

The authors introduce a method for cardiac investigations by using electrocardiographically gated spiral scanning with a four-section computed tomographic system. Three-dimensional images were reconstructed by means of a 250-msec temporal resolution and continuous volume coverage by using a dedicated multisection cardiac volume reconstruction algorithm. Motion-free thin-section volume images were acquired with thin sections and overlapping image increments within a single breath hold. Data segment shifts in time allowed for multiphase imaging.

View details for Web of Science ID 000090058800037

View details for PubMedID 11058661

View details for Web of Science ID 000088397500028

View details for PubMedID 10915687

View details for Web of Science ID 000087571900002

View details for PubMedID 10851219

View details for PubMedID 10769293

Abstract

Multi-row-detector-spiral-CT (MSCT) allows for 250 ms effective exposure time. The purpose of this study was to demonstrate the possibilities and limitations of this CT technology for non enhanced and contrast enhanced investigation of the coronary arteries.Investigation of the coronary arteries without contrast medium for quantification of coronary calcifications was performed in an obese patient (140 kg) with MSCT and electron beam CT (EBCT). In 56 patients contrast enhanced CT angiography of the coronary arteries was performed to determine image quality depending on the heart rate.In the obese patient superior image quality could be achieved with MSCT allowing for reliable quantification of coronary calcifications. With MSCT angiography of the coronary arteries good image quality was achieved in patients with a heart rate of 59 +/- 8 beats per minute.Even if there are limitations in patients with higher heart rates with an effective exposure time of 250 ms MSCT has clear advantage of image quality in the assessment of non enhanced and contrast enhanced coronary arteries.

View details for PubMedID 10758624

Abstract

To compare contrast agent-enhanced spiral and electron-beam computed tomography (CT) for the analysis of segmental and subsegmental pulmonary arteries.CT angiography of the pulmonary arteries was performed in 56 patients to rule out pulmonary embolism. Electron-beam CT was performed in 28 patients. The other 28 patients underwent spiral CT with comparable scanning protocols. The depiction of segmental and subsegmental arteries was analyzed by three independent readers. The contrast enhancement in the main pulmonary artery was measured in each patient.Analysis was performed in 1,120 segmental and 2, 240 subsegmental arteries. One segmental (RA7, P =.010) and two subsegmental (LA7b, P =.029; RA6a+b, P =.038) arteries in paracardiac and basal segments of the lung were depicted significantly better with electron-beam CT. There was no statistically significant difference between electron-beam and spiral CT in the total number of analyzable peripheral arteries depicted. The mean contrast enhancement in the main pulmonary artery was 362 HU in electron-beam CT studies versus 248 HU in spiral CT studies.Detailed visualization of peripheral pulmonary arteries is well within the scope of advanced CT techniques. Electron-beam CT has minor advantages in analyzing paracardiac arteries, probably because of reduction of motion artifacts and higher contrast enhancement. Further studies are needed to establish whether electron-beam CT allows a more confident diagnosis of emboli in these vessels.

View details for Web of Science ID 000085023400018

View details for PubMedID 10671591

Abstract

In this paper a method for cardiac imaging with fast multi-slice CT and retrospectively ECG-gated spiral acquisition is presented.A fast multi-slice CT system with 4 simultaneously acquired slices and 0.5 s rotation time is used (Siemens Somatom VolumeZoom). Continuous spiral data of the entire heart volume is acquired together with the patient's ECG and reconstructed with dedicated spiral algorithms providing 250 ms temporal resolution. Three-dimensional image data sets are built up from overlapping slices that are reconstructed in an arbitrary, user-defined phase of the heart cycle (e.g. diastolic phase). To evaluate the capability of the method for functional imaging complete three-dimensional image volumes are reconstructed from the same spiral data set in different phases of the heart cycle.A spiral data set of the entire heart volume may be acquired within a single breath-hold. Typical scan times for standard examinations with 3 mm slice width are 10-15 s, and for high-resolution CT angiographies of the coronary arteries with 1.25 mm slice width about 30-35 s. Motion-free reconstruction of the heart and coronary arteries with high spatial resolution is possible in the diastolic phase of the heart cycle. Multi-phase reconstructions from the same spiral scan data set are possible, however, motion artifacts in heart phases with fast cardiac motion may not be completely avoided.Fast multi-slice spiral CT with retrospectively ECG-gated spiral reconstruction is well suited for three-dimensional and functional imaging of the heart, especially for high-resolution imaging of calcified coronary plaques and CT-angiography of the coronary arteries.

View details for PubMedID 10758623

Abstract

We compared electron beam CT with conventional CT to determine the best method for the assessment of the coronary calcium score. We used conventional CT to examine symptomatic and asymptomatic patients suspected of having coronary artery disease.One hundred sixty male patients underwent electron beam CT and helical CT with a pitch of 1 (n = 30) and 2 (n = 30) and using a single-slice mode with (n = 50) and without (n = 50) prospective ECG triggering. In another 50 patients, we determined reproducibility for repeated scanning using electron beam CT. For all images, we derived the calcium score according to the Agatston method. We performed regression analysis and determined mean variability. Mean variability was calculated as the ratio of the absolute difference to the mean of the corresponding calcium scores.The correlation coefficients for electron beam CT and all conventional CT modes were very high (range, 0.93-0.98). The mean variability was highest in the helical mode with a pitch of 2 (61.4%) and lowest for the single-slice mode with prospective ECG triggering (25.4%). For repeated electron beam CT, the correlation coefficient and mean variability were 0.99 and 22.1%, respectively.ECG-triggered single-slice conventional CT had the best agreement with electron beam CT calcium scores.

View details for Web of Science ID 000084885000051

View details for PubMedID 10658740

Abstract

We describe the findings from various cross-sectional imaging modalities in patients with cardiac valve adherent masses. The techniques are discussed, and imaging findings are compared with the results of cardiac surgery. All three patients had neurological symptoms and/or cardiac murmurs. Transthoracic and/or transesophageal echocardiography revealed the cardiac mass in all three. For differentiation of thrombus and cardiac neoplasm magnetic resonance imaging (MRI) was also performed in all three patients and electron-beam computed tomography (EBCT) in two. Fast segmented cine gradient-echo MRI techniques provided mass depiction in all patients, while T1-weighted spin-echo imaging failed in mass detection in one patient. None of the patients showed evidence of valve regurgitation or stenosis in flow sensitive cine MRI. EBCT excluded mass calcifications in both patients and reliably demonstrated the valve attached lesions. Although echocardiography is the modality of choice in evaluating cardiac masses and especially valve attached masses, MRI and EBCT provide additional information about tissue characteristics and allows an excellent overview of the cardiac and paracardiac morphology. Fast segmented cine gradient-echo MRI is especially able to depict even small tumors attached to rapidly moving cardiac valves, and valve competence can be easily assessed within the same examination.

View details for Web of Science ID 000086150100008

View details for PubMedID 10756993

Abstract

This contribution reviews the pathology and morphology of coronary calcifications. It summarizes the indications for investigation of the coronary arteries. The standard protocols for scan acquisition using electron beam and conventional computed tomography are described as well as various methods for evaluation such as the traditional Agatston scoring method and the newer three-dimensional scoring algorithms. Guidelines for interpreting scores are also reviewed. Major limitations of the reproducibility of the calcium score measurement are summarized. Future aspects of multirow-detector spiral computed tomography with retrospective electrocardiographic triggering for quantifying coronary calcium are discussed.

View details for Web of Science ID 000088326000016

View details for PubMedID 10795546

Abstract

In this review the technical principles and applications of multi-slice CT are discussed. Multi-slice CT systems allow simultaneous acquisition of up to 4 slices by using multi-row detector systems. Intuitive geometrical arguments are used to establish the limitation to a maximum of 4 slices which is kept by all currently existing multi-slice CT systems. Two different construction principles of the detector are discussed, the "Fixed Array" detector and the "Adaptive Array" detector. The extension of conventional 360 LI and 180 LI spiral interpolation techniques to multi-slice spiral CT is explained as well as a new generalized multi-slice spiral weighting concept, the so-called "Adaptive Axial Interpolation". Several techniques to improve multi-slice spiral image quality are discussed. Finally, some examples for clinical applications are given, and the principle of ECG triggered and ECG gated cardiac examinations with optimized temporal resolution is presented. Multi-slice CT systems are a milestone with respect to increased volume coverage, shorter scan times, improved axial (longitudinal) resolution and better use of the X-ray tube output. Additionally, new clinical applications are possible such as Cardiac CT.

View details for PubMedID 10602796

Abstract

The purpose of this work was to compare image quality in phantom and patient CT scans acquired by xenon and ceramic CT detector systems.High and low contrast resolution and image noise were determined with a standard CT phantom for both detector systems. In patient CT images, the effect on image noise was measured in anatomical regions of interest in the head, lumbar spine, chest, and abdomen.In phantom studies, image noise was significantly lower using ceramic versus xenon detectors. Also, in images of the head and lumbar spine, the signal-to-noise ratio was significantly higher with ceramic than with xenon detectors. In chest scans, ceramic significantly reduced beam-hardening artifacts caused by the thoracic spine. However, in abdominal images, the signal-to-noise ratio was not significantly different between ceramic and xenon detector systems.For reduced image noise in CT images of the head, lumbar spine, and chest and high resolution CT, ceramic detector systems appear to be superior to xenon detector systems.

View details for Web of Science ID 000082885200030

View details for PubMedID 10524869

Abstract

To determine whether electrocardiographic (ECG) gating improves image quality of thin-section computed tomographic (CT) scans of the lung obtained with a subsecond CT scanner.Thin-section CT was performed in 35 patients by using standard techniques. Three additional sections were obtained in each patient with prospective ECG gating at corresponding levels of the paracardiac lung parenchyma. Non-ECG-gated and ECG-gated sections were then rated in blinded fashion by three experienced radiologists for overall image quality, spatial resolution, and diagnostic value and for different types of respiratory and cardiac motion artifacts.ECG gating helped significantly reduce artifacts caused by cardiac motion (i.e., distortion of pulmonary vessels, double images, or blurring of the cardiac border) (P < .05). ECG gating did not reduce respiratory motion artifacts. In patients with heart rates of less than 76 beats per minute, ECG gating significantly improved overall image quality (P = .041). ECG gating was not perceived to increase the diagnostic value of thin-section CT scans.ECG gating improves image quality of thin-section CT scans of the lung by reducing cardiac motion artifacts that may mimic disease. It must be established whether ECG gating can help increase the diagnostic accuracy of thin-section CT for the evaluation of subtle parenchymal disease.

View details for Web of Science ID 000082196600008

View details for PubMedID 10478227

Abstract

To identify patients with increased risk of having coronary artery disease (CAD), electron-beam computed tomography (EBCT) was used for years for quantifying calcifications of the coronary arteries. The first direct comparison between EBCT and conventional CT was performed to determine the reliability of widely available conventional CT for the assessment of the coronary calcium score. Fifty male patients with suspected CAD were investigated with both modalities, EBCT and conventional 500-ms non-spiral partial scan CT. Scoring of the coronary calcification was performed according to the Agatston method. Forty-two of these patients underwent coronary angiography for the assessment of significant luminal narrowing. The correlation coefficient of the score values of both modalities was highly significant (r = 0.982, p < 0.001). The variability between the two modalities was 42%. Mean calcium score in patients with significant coronary luminal narrowing (n = 37) was 1104 +/- 1089 with EBCT and 1229 +/- 1327 with conventional CT. In patients without luminal narrowing (n = 5) mean calcium score was 73 +/- 57 with EBCT and 26 +/- 35 with conventional CT. Although images of the heart from conventional CT may suffer from cardiac motion artifacts, conventional CT has the potential to identify patients with CAD with accuracy similar to EBCT.

View details for Web of Science ID 000080315900006

View details for PubMedID 10354872

Abstract

Coronary calcium is a powerful indicator of arteriosclerosis and can be detected very precisely with electron beam tomography. The method can be applied in patients with known coronary artery disease or in asymptomatic patients at risk of arteriosclerotic disease.The standard protocol of EBT consists of 30 to 40 slices of 3-mm thickness with a scan time of 100 ms, no overlap. No contrast medium is needed. The total scan can be performed within one breathhold. The calcium score is calculated as described by Agatston. Radiation exposure amounts to 0.8 mSv per total screen. We used spiral CT with and without ECG trigger as an alternative.At the University of Munich we performed an EBT scan of the heart in 1100 patients within the last year. In 567 patients coronary angiography was performed also (+/- 3 days). Confirming previous reports in the literature, we found a correlation of the calcium score with the age and gender of the patients. Severe coronary artery disease (stenoses > or = 75%) was associated with significantly more calcium than less severe CAD. The calcium score did not discriminate between one-, two- and three-vessel disease. The site of calcification does not correlate with the localization of stenoses. Thirty-three percent of the patients with significant coronary artery disease showed a normal age-adjusted calcium score; a total of 8.1% of patients with severe stenoses did not reveal any coronary calcification (score = 0). With asymptomatic patients there are only a few studies available. Soft plaques cannot be detected with EBT, but in most patients soft plaques occur together with hard plaques. Our results show that spiral CT of the newest generation may also be used for calcium screening. There was an excellent correlation of the calcium scores of EBT and spiral CT at all levels of calcification.Coronary calcium is a sensitive marker of coronary artery disease. In the clinical setting EBT is indicated in patients with known coronary artery disease (to evaluate prognosis), in patients who are unable to perform a stress test, and in patients with atypical chest pain. However, lack of calcification may be associated with severe stenoses in a minority of patients. The clinical value in asymptomatic patients needs to be defined: randomized studies are necessary. We see a possible indication in patients with known risk factors, in whom primary preventive strategies could be performed more selectively and cost-effectively.

View details for PubMedID 9931974

Abstract

To evaluate experimentally and in patients the sensitivity and effective dose of virtual electron-beam tomography (EBT) colonoscopy for detecting small colon tumors and to compare the methods and results with virtual colonoscopy using spiral CT and MR imaging in a review of the literature.Six polyps with diameters between 3 and 12 mm were created and randomly placed in resected pig colon. After distension with air, the pig colon was scanned with continuous volume scanning (CVS, 3 mm collimation) and a pitch of 0.4, 0.8 and 1.5. Twenty patients positive for the fecal blood test were examined after rectal CO2 insufflation and i.v. administration of 1 mg glucagon. A 13 s CVS scan was used to cover the entire colon within one breath-hold. 3D volume-rendered fly-throughs were evaluated by two independent radiologists. Effective dose equivalent was estimated using an Alderson phantom equipped with thermoluminescence dosimeters.In the tumor model, all polyps were detectable at a pitch of 1.5. A further reduction of the pitch ratio did not improve the conspicuity of the polyps. In patient studies, all tumors (n = 4) and polyps (n = 3) were correctly identified on 3D fly-throughs. Two false positive results were obtained. Effective dose equivalent was calculated at 3.2 mSv per scan.Our preliminary results indicate that virtual EBT colonoscopy holds promise for fast screening for colon polyps. The best technique for virtual colonoscopy (Spiral CT, EBT, MRI) has not yet been determined and the future role of virtual colonoscopy must still be defined.

View details for Web of Science ID 000076859800004

View details for PubMedID 9830662

Abstract

The objective of this study was to determine if digital luminescence mammography can be used as a diagnostic tool. We investigated twenty-two patients with mammographically suspicious findings using a conventional film-screen system and a digital phosphor storage plate in order to compare these two techniques. Four radiologists experienced in mammography reviewed each pair of images. Our results indicate that detectability of microcalcifications and solid masses with digital systems is superior to conventional film-screen mammography due to the increased contrast enhancement associated with digital systems. We did, however, find that characterization of morphological details is inferior with the digital system, presumably due to reduced spatial resolution. In addition, we found no statistically significant difference in the differentiation of benign from malignant lesions with both techniques. The accuracy of mammographic diagnosis was investigated in a receiver operating characteristic study and similar values were found with both techniques. Our results indicate that digital mammography will become an acceptable diagnostic tool although improvement, especially in spatial resolution, is desirable.

View details for PubMedID 9502757

Abstract

The direct left internal mammary artery (LIMA) bypass to the left anterior descending (LAD) without the use of extracorporal circulation through a small anterolateral thoracotomy has become established among the minimally invasive techniques in cardiac surgery. Technical difficulties may occur in patients with an enlarged left ventricle and subsequent lateral positioning of the LAD, a small LAD, or a small LIMA. We used electron beam tomography (EBT) for preoperative visualization of the topographical structures to seek out patients with potential technical difficulties.Eighteen patients, mean age 62 +/- 13 years, were entered in this study; in all cases the indication for revascularization was a significant stenosis of the LAD. Preoperatively an ECG-triggered EBT was performed. Following the image acquisition, a three-dimensional reconstruction of the data was performed. The LIMA, LAD, first diagonal branch, and chest wall were stained different colors for better visualization. Surgery was performed using a left anterolateral mini-thoracotomy and through this access, the LIMA was dissected and anastomosed using a stabilizer without the use of extracorporal circulation.In all but one of the 18 patients who had a preoperative EBT, the minimally invasive direct coronary artery bypass (MIDCAB) procedure was successfully performed using an anterolateral mini-thoracotomy. Based on the results of the EBT, the 5 centimeter incision was done parasternally in six patients, and more laterally (2-4 cm parasternally) in the other eleven cases. In 13 patients the access penetrated the fourth intercostal space; in four cases the fifth intercostal space was used. In one patient EBT revealed a very laterally positioned and diffusely arteriosclerotic LAD so the patient was operated using a median sternotomy, but without the use of extracorporal circulation. In all 18 patients the preoperatively acquired information of the anatomical topography was confirmed intraoperatively. One case without a preoperative EBT had to be converted to a conventional procedure due to a small, intramyocardial LAD and a very small LIMA. Postoperative angiography revealed patent LIMA grafts and uneventful anastomoses.For minimally invasive direct coronary artery bypass (MIDCAB) the topography of the LIMA, LAD and intercostal spaces is of major importance. Using the ECG-triggered EBT with subsequent three-dimensional reconstruction these relationships can be visualized. This enables an individual planning of the operation and a minimalization of the skin incision.

View details for PubMedID 11276449

Abstract

To compare the sensitivity of conventional spin-echo, fast spin-echo, fast fluid-attenuated inversion recovery (FLAIR), and turbo gradient spin-echo MR sequences in the detection of multiple sclerosis lesions.Conventional spin-echo, fast spin-echo, fast FLAIR, and turbo gradient spin-echo sequences were performed on a 1.0-T MR imager in seven patients with clinically definite multiple sclerosis. The images in each sequence were evaluated by two raters and consensus was reached by agreement.In comparing conventional spin-echo with fast spin-echo sequences, five lesions were seen only by conventional spin-echo and 63 were seen only by fast spin-echo; in comparing conventional spin-echo with fast FLAIR sequences, 18 lesions were seen only by conventional spin-echo and 109 only by fast FLAIR; in comparing conventional spin-echo with turbo gradient spin-echo sequences, 51 lesions were seen only by conventional spin-echo and seven only by turbo gradient spin-echo; in comparing fast spin-echo with fast FLAIR sequences, 45 lesions were seen only by fast spin-echo and 52 only by fast FLAIR.Fast spin-echo and fast FLAIR sequences improve the sensitivity of MR imaging in the detection of multiple sclerosis lesions with reduced acquisition time as compared with conventional spin-echo sequences. These sequences should therefore be considered for serial studies in patients with multiple sclerosis. The sensitivity of turbo gradient spin-echo was inferior to the other sequences, but its reduced acquisition time could make this technique the ideal choice for patients who cannot tolerate longer examination times.

View details for Web of Science ID A1997WZ04600022

View details for PubMedID 9159377

Abstract

Increasing percentages of digital modalities in radiology, in particular of digital image acquisition in conventional radiography, call for digital reporting, communication, and archiving techniques. These techniques are prerequisites for the "filmless" hospital. The first 2 have been covered extensively in the literature and by vendors. However, as regards online digital image archives there are still no satisfactory concepts available in the medical field. The present paper puts forward some suggestions as to how this situation could be improved.Analyses of radiology operations consider the prevailing PACS (picture archiving and communication system) archive concepts that use optical discs to be too small, too slow and too cumbersome to manage and therefore unable to function as comprehensive image archives for filmless hospitals. We suggest borrowing and adapting the well tested archive technologies from space research and the oil and broadcasting industries which have much higher capacities and speeds and better software interfacing possibilities. With such technologies the needs of filmless hospital operations can be met.A feasible concept for a transition strategy from conventional analog to digital archives is presented. Model calculations of the necessary investments and potential savings, including generous placement of viewing stations in the entire hospital, indicate amortization periods of 3.8-4.8 years.Alternative technologies for digital image archives already today make full-scale PACS for filmless hospitals technologically and conceptually feasible and financially mandatory.

View details for Web of Science ID A1996VZ65900002

View details for PubMedID 8995452