Bernd J. Wintersperger

Accuracy of 64-MDCT in the Diagnosis of Ischemic Heart Disease

OBJECTIVE 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). SUBJECTS AND METHODS 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. RESULTS 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. CONCLUSION 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.

Detection of hemodynamically significant coronary artery stenosis: incremental diagnostic value of dynamic CT-based myocardial perfusion imaging.

PURPOSE To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR). MATERIALS AND METHODS Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant. Subjects who were suspected of having or were known to have coronary artery disease underwent electrocardiographically triggered dynamic stress myocardial perfusion imaging. FFR measurement was performed within all main coronary arteries with a luminal narrowing of 50%-85%. Estimated myocardial blood flow (MBF) was derived from CT images by using a model-based parametric deconvolution method for 16 myocardial segments and was related to hemodynamically significant coronary artery stenosis with an FFR of 0.75 or less in a blinded fashion. Conventional measures of diagnostic accuracy were derived, and discriminatory power analysis was performed by using logistic regression analysis. RESULTS Of 36 enrolled subjects, 33 (mean age, 68.1 years ± 10 [standard deviation]; 25 [76%] men, eight [24%] women) completed the study protocol. An MBF cut point of 75 mL/100 mL/min provided the highest discriminatory power (C statistic, 0.707; P <.001). While the diagnostic accuracy of CT for the detection of anatomically significant coronary artery stenosis (>50%) was high, it was low for the detection of hemodynamically significant stenosis (positive predictive value [PPV] per coronary segment, 49%; 95% confidence interval [CI]: 36%, 60%). With use of estimated MBF to reclassify lesions depicted with CT angiography, 30 of 70 (43%) coronary lesions were graded as not hemodynamically significant, which significantly increased PPV to 78% (95% CI: 61%, 89%; P = .02). The presence of a coronary artery stenosis with a corresponding MBF less than 75 mL/100 mL/min had a high risk for hemodynamic significance (odds ratio, 86.9; 95% CI:17.6, 430.4). CONCLUSION Dynamic CT-based stress myocardial perfusion imaging may allow detection of hemodynamically significant coronary artery stenosis.

Image quality, motion artifacts, and reconstruction timing of 64-slice coronary computed tomography angiography with 0.33-second rotation speed.

Objectives:We sought to evaluate the impact of patients’ heart rate (HR) on coronary CTA image quality (IQ) and motion artifacts using a 64-slice scanner with 0.33/360° rotation. Materials and Methods:Coronary CTA data sets of 32 patients (HR ≤ 65 beats per minute [bpm], n = 15; HR > 65 bpm to ≤75 bpm, n = 10; HR > 75 bpm, n = 7) examined on a 64-slice scanner (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) with 0.33s/360° gantry rotation speed were analyzed. All patients had suspicion of coronary artery disease. Data acquisition was performed using 64 × 0.6-mm collimation, and contrast enhancement was provided by injection of 80 mL of iopromide (5 mL/s + NaCl). Images were reconstructed throughout the RR interval using half-scan and dual-segment reconstruction. IQ was rated by 2 observers using a 3-point scale from excellent (1) to nondiagnostic (3) for coronary segments. Quality was correlated to the HR, time point of optimal IQ analyzed, and the benefit of dual-segment reconstruction evaluated. Results:Overall mean IQ was 1.31 ± 0.32 for all HR, with IQ being 1.08 ± 0.12 for HR ≤ 65 bpm, 1.62 ± 0.27 for HR > 65 bpm ≤ 75 bpm and 1.36 ± 0.31 for HR > 75 bpm (P = 0.0003). Dual-segment reconstruction did not significantly improve IQ in any HR group (P = NS). Mean IQ was significantly better for LAD than for RCA (P < 0.0001) and LCX (P < 0.01). A total of 3.5% (11/318) of coronary artery segments were rated nondiagnostic by at least one reader based on motion artifacts. Although in HR < 65 bpm, the best IQ was predominately in diastole (93%), in HR > 75 bpm, the best IQ shifted to systole in most cases (86%). Conclusions:Temporal resolution at 0.33-second rotation allows for diagnostic IQ within a wide range of HR using half-scan reconstruction. With increasing HR the time point of best IQ shifts from mid-diastole to systole.

Diagnostic accuracy of dual-source computed tomography in the diagnosis of coronary artery disease.

Purpose: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. Materials and Methods: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 patients 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. Results: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. Conclusions: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.

ECG-Gated 64-MDCT Angiography in the Differential Diagnosis of Acute Chest Pain

OBJECTIVE 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. SUBJECTS AND METHODS 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. RESULTS 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. CONCLUSION 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.

Assessment of myocardial infarctions using multidetector-row computed tomography.

Objective: To evaluate the diagnostic power of contrast-enhanced multidetector-row computed tomography (MDCT) in assessing the presence, age, and size of myocardial infarctions. Methods: 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. Results: 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 cm3) 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]). Conclusions: 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.

High-resolution whole-body magnetic resonance imaging applications at 1.5 and 3 Tesla: a comparative study.

Objectives:To analyze the impact of altered magnetic field properties on image quality and on potential artifacts when an established whole-body magnetic resonance imaging (WB-MRI) protocol at 1.5 Tesla (T) is migrated to 3 T. Materials and Methods:Fifteen volunteers underwent noncontrast magnetic resonance imaging (MRI) on 32-channel whole body-scanners at 1.5 and 3 T with the use of parallel acquisition techniques (PAT). Coronal T1-weighted TSE- and short tau inversion recovery (STIR)-sequences at 4 body levels including sagittal imaging of the whole spine were performed. Additional axial HASTE-imaging of lung and abdomen, T1-/T2-weighted-TSE- and EPI-sequences of the brain and T2-weighted respiratory-triggered imaging of the liver was acquired. Both data sets were compared by 2 independent readers in respect to artifacts and image quality using a 5-point scale. Regions of pronounced artifacts were defined. Results:Overall image impression was both qualitatively rated as “good” at 1.5 and 3 T for T1-w-TSE- and STIR-imaging of the whole body and spine. At 1.5 T, significantly better quantitative values for overall image quality were found for WB-STIR, T2-w-TSE imaging of the liver and brain (Wilcoxon Mann–Whitney U Test; P < 0.05), overall rated as good at 3 T. Significantly higher dielectric effects at 3 T were affecting T1-w- and STIR-WB-MRI, and HASTE of the abdomen and better image homogeneity at 1.5 T was observed for T1-weighted-/STIR-WB-MRI and T1-w-TSE-imaging of the spine. Pulsation artifacts were significantly increased at 3 T for T1-w WB-MRI. Significantly higher susceptibility artifacts were found for GRE-sequences of the brain at 3 T. Motion artifacts, Gibbs-Ringing, and image distortion was not significantly different and showed slightly higher quantitative values at 3 T (except for HASTE imaging of the abdomen). Overall scan time was 45 minutes and 44 seconds at 1.5 T and 40 minutes and 28 seconds at 3 T at identical image resolution. Conclusion:Three Tesla WB-MRI is feasible with good image quality comparable to 1.5 T. 3.0 T WB-MRI shows significantly more artifacts with a mild to moderate impact on image assessment. Therefore 1.5 T WB-MRI is the preferred image modality. Overall scan time at 3 T is reduced with the use of parallel imaging at a constant image resolution.

Cardiac MRI in the assessment of cardiac injury and toxicity from cancer chemotherapy: a systematic review.

During the past 30 years, there has been a significant decrease in cancer mortality rates, predominantly attributable to improvements in treatment options.1 However, survivors are at increased risk of premature cardiac disease,2 both because of the overlap in risk factors for cancer and cardiovascular disease3 and the cardiotoxic effects of cancer chemotherapy. Two chemotherapeutic agent classes that are commonly associated with cardiotoxicity are the anthracyclines and tyrosine kinase inhibitors, both of which can cause left ventricular (LV) dysfunction and heart failure (HF).4,5 Mechanisms of cardiac injury from cancer therapy have been summarized elsewhere.4,6 Briefly, anthracycline cardiotoxicity has been attributed to reactive oxygen species formation, transcriptional changes in intracellular adenosine triphosphate production in cardiac myocytes, and, more recently, through interaction with cardiac topoisomerase IIβ.4,6 Trastuzumab cardiotoxicity seems to be because of inhibition of cardiomyocyte human epidermal growth factor receptor 2, resulting in ATP depletion and contractile dysfunction.4 Other proposed mechanisms include immune-mediated destruction of cardiomyocytes.4,6 At the tissue level, early anthracycline toxicity has been associated with myocardial inflammation,7–9 vacuolization,9–12 and cell swelling/edema.11,13 These changes seem to occur before myocardial functional abnormalities.11,13 Later stages of toxicity are associated with myocardial fibrosis.14,15 Unfortunately, the use of myocardial biopsy is not feasible for diagnostic purposes in this setting. However, once HF manifests, the 2-year mortality can be as high as 60%.16 This emphasizes the importance of early recognition of cardiac injury and institution of cardioprotective therapy in an effort to prevent development of HF and allow uninterrupted completion of cancer therapy.17 Thus, the diagnosis is dependent on either direct evidence of myocardial damage or functional disturbance. Either signal may be identified …

Noninvasive coronary angiography using dual-source computed tomography in patients with atrial fibrillation.

Objectives: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. Materials and Methods: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 patients 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 (≥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. Results: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. Conclusions: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.

Clinical Value of MDCT in the Diagnosis of Coronary Artery Disease in Patients with a Low Pretest Likelihood of Significant Disease

OBJECTIVE 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. SUBJECTS AND METHODS 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%), or significant 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. RESULTS 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. CONCLUSION 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.