Thomas Schlosser

Myocardial scar visualized by cardiovascular magnetic resonance imaging predicts major adverse events in patients with hypertrophic cardiomyopathy.

OBJECTIVES We sought to establish the prognostic value of a comprehensive cardiovascular magnetic resonance (CMR) examination in risk stratification of hypertrophic cardiomyopathy (HCM) patients. BACKGROUND With annual mortality rates ranging between 1% and 5%, depending on patient selection, a small but significant number of HCM patients are at risk for an adverse event. Therefore, the identification of and prophylactic therapy (i.e., defibrillator placement) in patients with HCM who are at risk of dying are imperative. METHODS Two-hundred forty-three consecutive patients with HCM were prospectively enrolled. All patients underwent initial CMR, and 220 were available for clinical follow-up. The mean follow-up time was 1,090 days after CMR. End points were all-cause and cardiac mortality. RESULTS During follow-up 20 of the 220 patients died, and 2 patients survived sudden cardiac death due to adequate implantable cardioverter-defibrillator discharge. Most events (n = 16) occurred for cardiac reasons; the remaining 6 events were related to cancer and accidents. Our data indicate that the presence of scar visualized by CMR yields an odds ratio of 5.47 for all-cause mortality and of 8.01 for cardiac mortality. This might be superior to classic clinical risk factors, because in our dataset the presence of 2 risk factors yields an odds ratio of 3.86 for all-cause and of 2.20 for cardiac mortality, respectively. Multivariable analysis also revealed the presence of late gadolinium enhancement as a good independent predictor of death in HCM patients. CONCLUSIONS Among our population of largely low or asymptomatic HCM patients, the presence of scar indicated by CMR is a good independent predictor of all-cause and cardiac mortality.

Myocardial late gadolinium enhancement: prevalence, pattern, and prognostic relevance in marathon runners.

PURPOSE To prospectively analyze the myocardial distribution of late gadolinium enhancement (LGE) with delayed-enhancement cardiac magnetic resonance (MR) imaging, to compare the prevalence of this distribution in nonprofessional male marathon runners with that in asymptomatic control subjects, and to examine the prognostic role of LGE. MATERIALS AND METHODS Institutional review board and ethics committee approval were obtained for this study, and all subjects provided written informed consent. Two-dimensional inversion-recovery segmented k-space gradient-echo MR sequences were performed after administration of a gadolinium-containing contrast agent in 102 ostensibly healthy male runners aged 50-72 years who had completed at least five marathons during the past 3 years and in 102 age-matched control subjects. Predominantly subendocardial regions of LGE typical of myocardial infarction (hereafter, coronary artery disease [CAD] pattern) were distinguished from a predominantly midmyocardial patchy pattern of LGE (hereafter, non-CAD pattern). Marathon runners with LGE underwent repeat cardiac MR imaging and additional adenosine perfusion imaging. Runners were followed up for a mean of 21 months +/- 3 (standard deviation) after initial presentation. The chi(2), Fisher exact, and McNemar exact tests were used for comparisons. Event-free survival rates were estimated with the Kaplan-Meier method, and overall group differences were evaluated with log-rank statistics. RESULTS Of the 102 runners, five had a CAD pattern of LGE, and seven had a non-CAD pattern of LGE. The CAD pattern of LGE was located in the territory of the left anterior descending coronary artery more frequently than was the non-CAD pattern (P = .0027, Fisher exact test). The prevalence of LGE in runners was higher than that in age-matched control subjects (12% vs 4%; P = .077, McNemar exact test). The event-free survival rate was lower in runners with myocardial LGE than in those without myocardial LGE (P < .0001, log-rank test). CONCLUSION Ostensibly healthy marathon runners have an unexpectedly high rate of myocardial LGE, and this may have diagnostic and prognostic relevance.

Hybrid PET/MR Imaging of the Heart: Feasibility and Initial Results

PURPOSE To assess the feasibility of hybrid imaging of the heart with fluorine 18 fluorodeoxyglucose (FDG) on an integrated 3-T positron emission tomography (PET)/magnetic resonance (MR) imaging system. MATERIALS AND METHODS The present study was approved by the local institutional review board. Written informed consent was obtained from all patients before imaging. Twenty consecutive patients with myocardial infarction (n = 20) underwent cardiac PET/MR imaging examination. Ten patients underwent additional cardiac PET/computed tomography (CT) before PET/MR. Two-dimensional half-Fourier acquisition single-shot turbo spin-echo sequences, balanced steady-state free precession cine sequences, two-dimensional turbo inversion-recovery magnitude T2-weighted sequences, and late gadolinium-enhanced (LGE) segmented two-dimensional inversion-recovery turbo fast low-angle shot sequences were performed. According to the 17-segment model, PET tracer uptake, wall motion, and late gadolinium enhancement were visually assessed for each segment on a binary scale, and categorical intermethod agreement was calculated by using the Cohen κ. The maximum standardized uptake value was measured in corresponding myocardial locations on PET/CT and PET/MR images. RESULTS Agreement was substantial over all patients and segments between PET and LGE images (κ = 0.76) and between PET and cine images (κ = 0.78). In 306 segments, 97 (32%) were rated as infarcted on PET images, compared with 93 (30%) rated as infarcted on LGE images and with 90 (29%) rated as infarcted on cine images. In a subgroup of patients (n = 10) with an additional PET/CT scan, no significant difference in myocardial tracer uptake between PET/CT and PET/MR images was found (paired t test, P = .95). CONCLUSION Cardiac PET/MR imaging with FDG is feasible and may add complementary information in patients with ischemic heart disease.

Assessment of left ventricular function and mass in patients undergoing computed tomography (CT) coronary angiography using 64-detector-row CT: comparison to magnetic resonance imaging

Purpose: To quantify left ventricular function and mass derived from retrospectively ECG-gated 64-detector-row computed tomography coronary angiography data sets in comparison to cine magnetic resonance (MR) imaging as the reference standard. We hypothesized that the administration of beta-blockers prior to multidetector computed tomography (MDCT) coronary angiography has a significant impact on left ventricular functional parameters. Material and Methods: Multiplanar reformations in the short-axis orientation were calculated from axial contrast-enhanced CT images in 21 patients (16 male, five female; age range 41–75 years, mean 64.3±6.8 years) referred for CT coronary angiography. Patients whose heart rates exceeded 60 bpm received 5 mg bisoprolol orally 1 hour before the MDCT examination. In case of insufficient heart-rate reduction, up to four vials (20 mg) of metoprolol were injected intravenously. The end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), cardiac output (CO), and left ventricular mass (LVM) of the reformatted images were analyzed compared to volumetric measurements based on continuous short-axis steady-state free-precession cine MR sequences (TR 3 ms, TE 1.5 ms, FA 60°). Results: On average, each patient received 15.5 mg metoprolol (range 0–20 mg) and 3.85 mg bisoprolol (range 0–5 mg). The mean heart rate was 56±5 bpm during CT and 73±9 bpm during MRI examination. This difference was statistically significant (P<0.05). Mean EDV and ESV measured on MDCT were significantly higher compared to MR (MDCT vs. MR: EDV 164.2±52.5 vs. 144.2±46.7 ml, ESV 77.3±46.6 vs. 63.8±47.3 ml; P<0.05). Mean EF and CO derived from MDCT images were significantly lower compared to MR (MDCT vs. MR: EF 55.4±11.8 vs. 59.3±15.4%, CO 4822±779 vs. 5755±1267 ml; P<0.05). Mean SV and LVM were not significantly different between both methods (MDCT vs. MR: SV 86.8±18.1 vs. 80.3±15.6 ml, P = 0.44; LVM 132.4±42.5 vs. 138.7±39.1 g, P = 0.31). Conclusion: Left ventricular volumes assessed by the newest-generation MDCT scanners are significantly higher compared with MRI, whereas ejection fraction and cardiac output are significantly lower in MDCT. This appears to be a result of the frequent application of beta-blockers prior to MDCT examinations.

Simultaneous 18F choline positron emission tomography/magnetic resonance imaging of the prostate: initial results.

PurposeThe purposes of this study were to evaluate the feasibility of simultaneous 18F choline positron emission tomography (PET) and magnetic resonance imaging (MRI) of the prostate and to present the first clinical results of the method. Materials and MethodsFrom March 2012 to October 2012, a total of 15 consecutive patients were examined with simultaneous 18F choline PET/MRI. At the time of the examination, 8 patients had histologically proven prostate cancer, 2 patients had repeated prostate biopsies with negative results, and 5 patients had suspected prostate cancer with an elevated or rising prostate specific antigene level but did not have a prostate biopsy. Sequence protocol comprised T2-weighted high-resolution images and diffusion-weighted images of the prostate in addition to PET imaging. Image quality was assessed by 2 radiologists, and the PET images were evaluated qualitatively and quantitatively. ResultsSimultaneous PET/MRI of the prostate was accomplished successfully in all patients. The method proved to be robust without technical failure, and the image quality was rated to be diagnostic in all examinations except in 1 diffusion-weighted imaging (DWI) data set that was judged to be nondiagnostic because of susceptibility artifacts. High-resolution T2-weighted images allowed exact correlation of elevated focal or diffuse choline uptake to suspicious T2-weighted lesions of the prostate. A high accordance was found between PET and DWI. However, PET-positive lesions were found in 3 patients wherein DWI did not indicate tumor in suspicious T2-weighted lesions. ConclusionsSimultaneous positron emission tomography/magnetic resonance imaging of the prostate has the advantage of combining high-resolution prostate images, functional studies, and metabolic/molecular imaging. The PET component adds diagnostic confidence to the MRI-based parameters in identifying and localizing tumor in the prostate.

Right Ventricular Involvement in Acute Left Ventricular Myocardial Infarction: Prognostic Implications of MRI Findings

OBJECTIVE The purpose of this study was to investigate the prevalence and prognostic importance of the cardiac MRI finding of right ventricular involvement in patients with acute ST-segment elevation myocardial infarction (MI). SUBJECTS AND METHODS Fifty patients (41 men, nine women; mean age, 58 +/- 11 years) with first-ST-segment elevation MI underwent 1.5-T cardiac MRI immediately after successful percutaneous coronary intervention. The cardiac MRI protocol included steady-state free precession cine sequences for functional assessment of the left, right, and both ventricles and inversion recovery FLASH delayed enhancement sequences after contrast administration for the quantification of myocardial damage. The prevalence of right ventricular involvement detected with ECG and echocardiography was compared with the prevalence detected with cardiac MRI, which was the reference standard. Patients underwent follow-up for 32 +/- 8 months. RESULTS Right ventricular involvement was diagnosed with cardiac MRI in 27 patients (54%): 14 of 30 patients (47%) with inferior ST-segment elevation MI and 13 of 20 patients (65%) with anterior ST-segment elevation MI. ECG and echocardiographic findings showed only moderate agreement with cardiac MRI findings in the detection of right ventricular involvement in inferior acute MI (kappa = 0.38). Patients with right ventricular involvement in anterior ST-segment elevation MI had larger infarcts (delayed enhancement, 25.9% +/- 14.5% vs 11.4% +/- 10.1%; p = 0.030), lower left ventricular ejection fraction (34.3% +/- 8.2% vs 45.2% +/- 9.5%; p < 0.015), and lower right ventricular ejection fraction (39.8% +/- 6.6% vs 54.9% +/- 8.8%; p < 0.001) than those without right ventricular involvement. In a multivariate logistic regression model, right ventricular involvement was a strong independent predictor (odds ratio, 15.8; 95% CI, 4-63%) of major cardiac adverse events. CONCLUSION Right ventricular involvement in ST-segment elevation MI is detected more frequently with cardiac MRI than with ECG and echocardiography and is an independent prognostic indicator.

Integrated 18F-FDG PET/MR Imaging in the Assessment of Cardiac Masses: A Pilot Study

The objective of the present study was to evaluate whether integrated 18F-FDG PET/MR imaging could improve the diagnostic workup in patients with cardiac masses. Methods: Twenty patients were prospectively assessed using integrated cardiac 18F-FDG PET/MR imaging: 16 patients with cardiac masses of unknown identity and 4 patients with cardiac sarcoma after surgical therapy. All scans were obtained on an integrated 3-T PET/MR device. The MR protocol consisted of half Fourier acquisition single-shot turbo spin-echo sequence, cine, and T2-weighted images as well as T1-weighted images before and after injection of gadobutrol. PET data were acquired simultaneously with the MR scan after injection of 199 ± 58 MBq of 18F-FDG. Patients were prepared with a high-fat, low-carbohydrate diet in a period of 24 h before the examination, and 50 IU/kg of unfractionated heparin were administered intravenously 15 min before 18F-FDG injection. Results: Cardiac masses were diagnosed as follows: metastases, 3; direct tumor infiltration via pulmonary vein, 1; local relapse of primary sarcoma after surgery, 2; Burkitt lymphoma, 1; scar/patch tissue after surgery of primary sarcoma, 2; myxoma, 4; fibroelastoma, 1; caseous calcification of mitral annulus, 3; and thrombus, 3. The maximum standardized uptake value (SUVmax) in malignant lesions was significantly higher than in nonmalignant cases (13.2 ± 6.2 vs. 2.3 ± 1.2, P = 0.0004). When a threshold of 5.2 or greater was used, SUVmax was found to yield 100% sensitivity and 92% specificity for the differentiation between malignant and nonmalignant cases. T2-weighted hyperintensity and contrast enhancement both yielded 100% sensitivity but a weak specificity of 54% and 46%, respectively. Morphologic tumor features as assessed by cine MR imaging yielded 86% sensitivity and 92% specificity. Consent interpretation using all available MR features yielded 100% sensitivity and 92% specificity. A Boolean ‘AND’ combination of an SUVmax of 5.2 or greater with consent MR image interpretation improved sensitivity and specificity to 100%. Conclusion: In selected patients, 18F-FDG PET/MR imaging can improve the noninvasive diagnosis and follow-up of cardiac masses.

Evaluation of the PET component of simultaneous [ 18 F]choline PET/MRI in prostate cancer: comparison with [ 18 F]choline PET/CT

PurposeThe aim of this study was to evaluate the positron emission tomography (PET) component of [18F]choline PET/MRI and compare it with the PET component of [18F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer.MethodsThirty-six patients were examined with simultaneous [18F]choline PET/MRI following combined [18F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUVmax and SUVmean) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUVmax and SUVmean was tested using Pearson’s product-moment correlation and Bland-Altman analysis.ResultsAll PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUVmax and SUVmean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p < 0.05 and 2.0 vs 2.6, p < 0.001, respectively). Pearson’s product-moment correlation indicated highly significant correlations between SUVmax of PET/CT and PET/MRI (R = 0.86, p < 0.001) as well as between SUVmean of PET/CT and PET/MRI (R = 0.81, p < 0.001). Bland-Altman analysis revealed lower and upper limits of agreement of −2.77 to 3.64 between SUVmax of PET/CT vs PET/MRI and −1.12 to +2.23 between SUVmean of PET/CT vs PET/MRI.ConclusionPET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUVmax and SUVmean was found. Both SUVmax and SUVmean were significantly lower in [18F]choline PET/MRI than in [18F]choline PET/CT. Differences of SUVmax and SUVmean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [18F]choline between the subsequent examinations and in the respective organ systems have to be taken into account.

Noninvasive coronary angiography using 64-detector-row computed tomography in patients with a low to moderate pretest probability of significant coronary artery disease.

Purpose: To evaluate the value of 64-detector-row computed tomography for ruling out high-grade coronary stenoses in patients with a low to moderate pretest probability of significant coronary artery disease. Material and Methods: The study included 61 patients with a suspicion of coronary artery disease on the basis of atypical angina or ambiguous findings in noninvasive stress testing and a class II indication for invasive coronary angiography (ICA). All patients were examined by 64-detector-row computed tomography angiography (CTA) and ICA. On a coronary segmental level, the presence of significant (⩾50% diameter) stenoses was examined. Results: In a total of 915 segments, CTA detected 62 significant stenoses. Thirty-four significant stenoses were confirmed by ICA, whereas 28 stenoses could not be confirmed by ICA. Twenty-two of them showed wall irregularities on ICA, and six were angiographically normal. Accordingly, on a coronary segmental basis, 28 false-positive and 0 false-negative findings resulted in a sensitivity of 100%, a specificity of 96.8%, a positive predictive value of 54.8%, and a negative predictive value of 100%. The diagnostic accuracy was 96.9%. Conclusion: Sixty-four-detector-row computed tomography reliably detects significant coronary stenoses in patients with suspected coronary artery disease and appears to be helpful in the selection of patients who need to undergo ICA. Calcified and non-calcified plaques are detected. Grading of stenoses in areas with calcification is difficult. Frequently, stenosis severity is overestimated by 64-detector-row computed tomography.

Late Enhancement: A New Feature in MRI of Arrhythmogenic Right Ventricular Cardiomyopathy?

Aim of the study was to evaluate whether late enhancement (LE) in contrast-enhanced MRI can be used to characterize fibrofatty myocardial replacement in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC). Fifteen patients with suspected ARVC underwent CE-MRI using a 1.5 T scanner. Long and short axis SSFP cine images and T1-weighted fast spin echo images were collected in all patients. After injection of 0.2 mmol/kg Gd-DTPA (Magnevist, Schering, Berlin, Germany), inversion recovery gradient echo images were acquired in long and contiguous short axes to detect myocardial LE indicating areas of fibrous tissue within the myocardium. For definition of ARVC, the ESC Task force criteria were used. In 7 (47%) of 15 patients, ARVC was diagnosed based on the ESC criteria. In all of these 7 patients, MRI showed morphologic or functional criteria of ARVC according to the ESC. LE of the right ventricular myocardium was detected in 5 (71%) of the 7 ARVC patients, additional LE of the left ventricular myocardium in 2 of these patients. None of the 7 patients meeting the ARVC diagnostic criteria had fatty RV infiltration demonstrable by conventional T1-weighted imaging. Eight patients neither showed morphologic criteria of ARVC nor LE. In conclusion, late enhancement can be detected in the right and left ventricular myocardium in some ARVC patients. LE might represent intramyocardial areas of fibrous tissue.