Reproducibility assessment of rapid strains in cardiac MRI: Insights and recommendations for clinical application.

PURPOSE: Studies have shown the incremental value of strain imaging in various cardiac diseases. However, reproducibility and generalizability has remained an issue of concern. To overcome this, simplified algorithms such as rapid atrioventricular strains have been proposed. This multicenter study aimed to assess the reproducibility of rapid strains in a real-world setting and identify potential predictors for higher interobserver variation. METHODS: A total of 4 sites retrospectively identified 80 patients and 80 healthy controls who had undergone cardiac magnetic resonance imaging (CMR) at their respective centers using locally available scanners with respective field strengths and imaging protocols. Strain and volumetric parameters were measured at each site and then independently re-evaluated by a blinded core lab. Intraclass correlation coefficients (ICC) and Bland-Altman plots were used to assess inter-observer agreement. In addition, backward multiple linear regression analysis was performed to identify predictors for higher inter-observer variation. RESULTS: There was excellent agreement between sites in feature-tracking and rapid strain values (ICC ≥ 0.96). Bland-Altman plots showed no significant bias. Bi-atrial feature-tracking and rapid strains showed equally excellent agreement (ICC ≥ 0.96) but broader limits of agreement (≤18.0 % vs. ≤3.5 %). Regression analysis showed that higher field strength and lower temporal resolution (>30 ms) independently predicted reduced interobserver agreement for bi-atrial strain parameters (ß = 0.38, p = 0.02 for field strength and ß = 0.34, p = 0.02 for temporal resolution). CONCLUSION: Simplified rapid left ventricular and bi-atrial strain parameters can be reliably applied in a real-world multicenter setting. Due to the results of the regression analysis, a minimum temporal resolution of 30 ms is recommended when assessing atrial deformation.

Automated image quality assessment for selecting among multiple magnetic resonance image acquisitions in the German National Cohort study.

In magnetic resonance imaging (MRI), the perception of substandard image quality may prompt repetition of the respective image acquisition protocol. Subsequently selecting the preferred high-quality image data from a series of acquisitions can be challenging. An automated workflow may facilitate and improve this selection. We therefore aimed to investigate the applicability of an automated image quality assessment for the prediction of the subjectively preferred image acquisition. Our analysis included data from 11,347 participants with whole-body MRI examinations performed as part of the ongoing prospective multi-center German National Cohort (NAKO) study. Trained radiologic technologists repeated any of the twelve examination protocols due to induced setup errors and/or subjectively unsatisfactory image quality and chose a preferred acquisition from the resultant series. Up to 11 quantitative image quality parameters were automatically derived from all acquisitions. Regularized regression and standard estimates of diagnostic accuracy were calculated. Controlling for setup variations in 2342 series of two or more acquisitions, technologists preferred the repetition over the initial acquisition in 1116 of 1396 series in which the initial setup was retained (79.9%, range across protocols: 73-100%). Image quality parameters then commonly showed statistically significant differences between chosen and discarded acquisitions. In regularized regression across all protocols, 'structured noise maximum' was the strongest predictor for the technologists' choice, followed by 'N/2 ghosting average'. Combinations of the automatically derived parameters provided an area under the ROC curve between 0.51 and 0.74 for the prediction of the technologists' choice. It is concluded that automated image quality assessment can, despite considerable performance differences between protocols and anatomical regions, contribute substantially to identifying the subjective preference in a series of MRI acquisitions and thus provide effective decision support to readers.

Cardiovascular disease in women: insights from magnetic resonance imaging.

The presentation and identification of cardiovascular disease in women pose unique diagnostic challenges compared to men, and underrecognized conditions in this patient population may lead to clinical mismanagement.This article reviews the sex differences in cardiovascular disease, explores the diagnostic and prognostic role of cardiovascular magnetic resonance (CMR) in the spectrum of cardiovascular disorders in women, and proposes the added value of CMR compared to other imaging modalities. In addition, this article specifically reviews the role of CMR in cardiovascular diseases occurring more frequently or exclusively in female patients, including Takotsubo cardiomyopathy, connective tissue disorders, primary pulmonary arterial hypertension and peripartum cardiomyopathy. Gaps in knowledge and opportunities for further investigation of sex-specific cardiovascular differences by CMR are also highlighted.

Comparability of compressed sensing-based gradient echo perfusion sequence SPARSE and conventional gradient echo sequence in assessment of myocardial ischemia.

PURPOSE: Stress perfusion imaging plays a major role in non-invasive detection of coronary artery disease. We compared a compressed sensing-based and a conventional gradient echo perfusion sequence with regard to image quality and diagnostic performance. METHOD: Patients sent for coronary angiography due to pathologic stress perfusion CMR were recruited. All patients underwent two adenosine stress CMR using conventional TurboFLASH and prototype SPARSE sequence as well as quantitative coronary angiography with fractional flow reserve (FFR) within 6 weeks. Coronary angiography was considered gold standard with FFR < 0.75 or visual stenosis >90 % for identification of myocardial ischemia. Diagnostic performance of perfusion imaging was assessed in basal, mid-ventricular and apical slices by quantification of myocardial perfusion reserve (MPR) analysis utilizing the signal upslope method and a deconvolution technique using the fermi function model. RESULTS: 23 patients with mean age of 69.6 ± 8.9 years were enrolled. 46 % were female. Image quality was similar in conventional TurboFLASH sequence and SPARSE sequence (2.9 ± 0.5 vs 3.1 ± 0.7, p = 0,06). SPARSE sequence showed higher contrast-to-noise ratio (52.1 ± 27.4 vs 40.5 ± 17.6, p < 0.01) and signal-to-noise ratio (15.6 ± 6.2 vs 13.2 ± 4.2, p < 0.01) than TurboFLASH sequence. Dark-rim artifacts occurred less often with SPARSE (9 % of segments) than with TurboFLASH (23 %). In visual assessment of perfusion defects, SPARSE sequence detected less false-positive perfusion defects (n = 1) than TurboFLASH sequence (n = 3). Quantitative perfusion analysis on segment basis showed equal detection of perfusion defects for TurboFLASH and SPARSE with both upslope MPR analysis (TurboFLASH 0.88 ± 0.18; SPARSE 0.77 ± 0.26; p = 0.06) and fermi function model (TurboFLASH 0.85 ± 0.24; SPARSE 0.76 ± 0.30; p = 0.13). CONCLUSIONS: Compressed sensing perfusion imaging using SPARSE sequence allows reliable detection of myocardial ischemia.

Assessment of diastolic dysfunction: comparison of different cardiovascular magnetic resonance techniques.

AIMS: Heart failure with preserved ejection fraction is still a diagnostic and therapeutic challenge, and accurate non-invasive diagnosis of left ventricular (LV) diastolic dysfunction (DD) remains difficult. The current study aimed at identifying the most informative cardiovascular magnetic resonance (CMR) parameters for the assessment of LVDD. METHODS AND RESULTS: We prospectively included 50 patients and classified them into three groups: with DD (DD+, n = 15), without (DD-, n = 26), and uncertain (DD±, n = 9). Diagnosis of DD was based on echocardiographic E/E', invasive LV end-diastolic pressure, and N-terminal pro-brain natriuretic peptide. CMR was performed at 1.5 T to assess LV and left atrial (LA) morphology, LV diastolic strain rate (SR) by tissue tracking and tagging, myocardial peak velocities by tissue phase mapping, and transmitral inflow profile using phase contrast techniques. Statistics were performed only on definitive DD+ and DD- (total number 41). DD+ showed enlarged LA with LA end-diastolic volume/height performing best to identify DD+ with a cut-off value of ≥0.52 mL/cm (sensitivity = 0.71, specificity = 0.84, and area under the receiver operating characteristic curve = 0.75). DD+ showed significantly reduced radial (inferolateral E peak: DD-: -14.5 ± 6.5%/s vs. DD+: -10.9 ± 5.9%/s, P = 0.04; anterolateral A peak: DD-: -4.2 ± 1.6%/s vs. DD+: -3.1 ± 1.4%/s, P = 0.04) and circumferential (inferolateral A peak: DD-: 3.8 ± 1.2%/s vs. DD+: 2.8 ± 0.8%/s, P = 0.007; anterolateral A peak: DD-: 3.5 ± 1.2%/s vs. DD+: 2.5 ± 0.8%/s, P = 0.048) SR in the basal lateral wall assessed by tissue tracking. In the same segments, DD+ showed lower peak myocardial velocity by tissue phase mapping (inferolateral radial peak: DD-: -3.6 ± 0.7 ms vs. DD+: -2.8 ± 1.0 ms, P = 0.017; anterolateral longitudinal peak: DD-: -5.0 ± 1.8 ms vs. DD+: -3.4 ± 1.4 ms, P = 0.006). Tagging revealed reduced global longitudinal SR in DD+ (DD-: 45.8 ± 12.0%/s vs. DD+: 34.8 ± 9.2%/s, P = 0.022). Global circumferential and radial SR by tissue tracking and tagging, LV morphology, and transmitral flow did not differ between DD+ and DD-. CONCLUSIONS: Left atrial size and regional quantitative myocardial deformation applying CMR identified best patients with DD.

Cost-Effectiveness Analysis of Stress Cardiovascular Magnetic Resonance Imaging for Stable Chest Pain Syndromes.

OBJECTIVES: The aim of this study was to compare, using results from the multicenter SPINS (Stress CMR Perfusion Imaging in the United States) study, the incremental cost-effectiveness of a stress cardiovascular magnetic resonance (CMR)-first strategy against 4 other clinical strategies for patients with stable symptoms suspicious for myocardial ischemia: 1) immediate x-ray coronary angiography (XCA) with selective fractional flow reserve for all patients; 2) single-photon emission computed tomography; 3) coronary computed tomographic angiography with selective computed tomographic fractional flow reserve; and 4) no imaging. BACKGROUND: Stress CMR perfusion imaging has established excellent diagnostic utility and prognostic value in coronary artery disease (CAD), but its cost-effectiveness in current clinical practice has not been well studied in the United States. METHODS: A decision analytic model was developed to project health care costs and lifetime quality-adjusted life years (QALYs) for symptomatic patients at presentation with a 32.4% prevalence of obstructive CAD. Rates of clinical events, costs, and quality-of-life values were estimated from SPINS and other published research. The analysis was conducted from a U.S. health care system perspective, with health and cost outcomes discounted annually at 3%. RESULTS: Using hard cardiovascular events (cardiovascular death or acute myocardial infarction) as the endpoint, total costs per person were lowest for the no-imaging strategy ($16,936) and highest for the immediate XCA strategy ($20,929). Lifetime QALYs were lowest for the no-imaging strategy (12.72050) and highest for the immediate XCA strategy (12.76535). The incremental cost-effectiveness ratio for the CMR-based strategy compared with the no-imaging strategy was $52,000/QALY, whereas the incremental cost-effectiveness ratio for the immediate XCA strategy was $12 million/QALY compared with CMR. Results were sensitive to variations in model inputs for prevalence of disease, hazard rate ratio for treatment of CAD, and annual discount rate. CONCLUSIONS: Prior to invasive XCA, stress CMR can be a cost-effective gatekeeping tool in patients at risk for obstructive CAD in the United States. (Stress CMR Perfusion Imaging in the United States [SPINS] Study; NCT03192891.

Correction to: Subclinical myocardial injury in patients with Facioscapulohumeral muscular dystrophy 1 and preserved ejection fraction - assessment by cardiovascular magnetic resonance.

In the original version of this article [1], published on 29 April 2019, there is 1 error in the 'Method' section of the article.

Subclinical myocardial injury in patients with Facioscapulohumeral muscular dystrophy 1 and preserved ejection fraction - assessment by cardiovascular magnetic resonance.

BACKGROUND: Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is an autosomal dominant and the third most common inherited muscle disease. Cardiac involvement is currently described in several muscular dystrophies (MD), but there are conflicting reports in FSHD1. Mostly, FSHD1 is recognized as MD with infrequent cardiac involvement, but sudden cardiac deaths are reported in single cases. The aim of this study is to investigate whether subclinical cardiac involvement in FSHD1 patients is detectable in preserved left ventricular systolic function applying cardiovascular magnetic resonance (CMR). METHODS: We prospectively included patients with genetically confirmed FSHD1 (n = 52, 48 ± 15 years) and compared them with 29 healthy age-matched controls using a 1.5 T CMR scanner. Myocardial tissue differentiation was performed qualitatively using focal fibrosis imaging (late gadolinium enhancement (LGE)), fat imaging (multi-echo sequence for fat/water-separation) and parametric T2- and T1-mapping for quantifying inflammation and diffuse fibrosis. Extracellular volume fraction was calculated. A 12-lead electrocardiogram and 24-h Holter were performed for the assessment of MD-specific Groh-criteria and arrhythmia. RESULTS: Focal fibrosis by LGE was present in 13 patients (25%,10 men), fat infiltration in 7 patients (13%,5 men). T2 values did not differ between FSHD1 and healthy controls. Native T1 mapping revealed significantly higher values in patients (global native myocardial T1 values basal: FSHD1: 1012 ± 26 ms vs. controls: 985 ± 28 ms, p < 0.01, medial FSHD1: 994 ± 37 ms vs. controls: 982 ± 28 ms, p = 0.028). This was also evident in regions adjacent to focal fibrosis, indicating diffuse fibrosis. Groh-criteria were positive in 1 patient. In Holter, arrhythmic events were recorded in 10/43 subjects (23%). CONCLUSIONS: Patients with FSHD1 and preserved left ventricular ejection fraction present focal and diffuse myocardial injury. Longitudinal multi-center trials are needed to define the impact of myocardial changes as well as a relation between myocardial injury and arrhythmias on long-term prognosis and therapeutic decision-making. TRIAL REGISTRATION: ISRCTN registry with study ID ISRCTN13744381 .

Quantification in cardiovascular magnetic resonance: agreement of software from three different vendors on assessment of left ventricular function, 2D flow and parametric mapping.

BACKGROUND: Quantitative results of cardiovascular magnetic resonance (CMR) image analysis influence clinical decision making. Image analysis is performed based on dedicated software. The manufacturers provide different analysis tools whose algorithms are often unknown. The aim of this study was to evaluate the impact of software on quantification of left ventricular (LV) assessment, 2D flow measurement and T1- and T2-parametric mapping. METHODS: Thirty-one data sets of patients who underwent a CMR Scan on 1.5 T were analyzed using three different software (Circle CVI: cvi42, Siemens Healthineers: Argus, Medis: Qmass/Qflow) by one reader blinded to former results. Cine steady state free precession short axis images were analyzed regarding LV ejection fraction (EF), end-systolic and end-diastolic volume (ESV, EDV) and LV mass. Phase-contrast magnetic resonance images were evaluated for forward stroke volume (SV) and peak velocity (Vmax). Pixel-wise generated native T1- and T2-maps were used to assess T1- and T2-time. Forty-five data sets were evaluated twice (15 per software) for intraobserver analysis. Equivalence was considered if the confidence interval of a paired assessment of two sofware was within a tolerance interval defined by ±1.96 highest standard deviation obtained by intraobserver analysis. RESULTS: For each parameter, thirty data sets could be analyzed with all three software. All three software (A/B, A/C, B/C) were considered equivalent for LV EF, EDV, ESV, mass, 2D flow SV and T2-time. Differences between software were detected in flow measurement for Vmax and in parametric mapping for T1-time. For Vmax, equivalence was given between software A and C and for T1-time equivalence was given between software B and C. CONCLUSION: Software had no impact on quantitative results of LV assessment, T2-time and SV based on 2D flow. In contrast to that, Vmax and T1-time may be influenced by software. CMR reports should contain the name and version of the software applied for image analysis to avoid misinterpretation upon follow-up and research examinations. TRIAL REGISTRATION: ISRCTN12210850 . Registered 14 July 2017, retrospectively registered.

Functional LGE Imaging: Cardiac Phase-Resolved Assessment of Focal Fibrosis.

Cardiac Magnetic Resonance Imaging (CMR) is a central tool for diagnosis of various ischemic and non-ischemic cardiomyopathies. CMR protocols commonly comprise assessment of functional properties using cardiac phase-resolved CINE MRI and characterization of myocardial viability using late gadolinium enhancement (LGE) imaging. Conventional LGE imaging requires inversion recovery preparation with a specific inversion time to null the healthy myocardium, which restricts the acquisition to a single cardiac phase. In turn, this necessitates separate scans for cardiac function and viability. In this work, we develop a new method for functional LGE imaging in a single breath-hold using a three-step approach: 1) ECG-triggered multi-contrast data is acquired for each cardiac phase, 2) semi-quantitative relaxation maps are generated, 3) LGE imaging contrast is synthesized based on the semi-quantitative maps. The proposed functional LGE method is evaluated in four healthy subject and 20 patients at 1.5T and 3T. Thorough suppression of the healthy myocardium, as well as 40-80ms temporal resolution are achieved, with no visually apparent temporal blurring at tissue interfaces. Functional LGE in patients with focal scar demonstrates robust hyperenhancement in the scar area throughout all cardiac phases, allowing for visual assessment of scar motility. The proposed technique bears the potential to simplify and speedup common cardiac imaging protocols, while enabling improved data fusion of functional and viability information for improved evaluation of CMR.

Temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ): Dynamic myocardial T1 mapping using a cine steady-state look-locker approach.

PURPOSE: To develop and evaluate a cardiac phase-resolved myocardial T1 mapping sequence. METHODS: The proposed method for temporally resolved parametric assessment of Z-magnetization recovery (TOPAZ) is based on contiguous fast low-angle shot imaging readout after magnetization inversion from the pulsed steady state. Thereby, segmented k-space data are acquired over multiple heartbeats, before reaching steady state. This results in sampling of the inversion-recovery curve for each heart phase at multiple points separated by an R-R interval. Joint T1 and B1+ estimation is performed for reconstruction of cardiac phase-resolved T1 and B1+ maps. Sequence parameters are optimized using numerical simulations. Phantom and in vivo imaging are performed to compare the proposed sequence to a spin-echo reference and saturation pulse prepared heart rate-independent inversion-recovery (SAPPHIRE) T1 mapping sequence in terms of accuracy and precision. RESULTS: In phantom, TOPAZ T1 values with integrated B1+ correction are in good agreement with spin-echo T1 values (normalized root mean square error = 4.2%) and consistent across the cardiac cycle (coefficient of variation = 1.4 ± 0.78%) and different heart rates (coefficient of variation = 1.2 ± 1.9%). In vivo imaging shows no significant difference in TOPAZ T1 times between the cardiac phases (analysis of variance: P = 0.14, coefficient of variation = 3.2 ± 0.8%), but underestimation compared with SAPPHIRE (T1 time ± precision: 1431 ± 56 ms versus 1569 ± 65 ms). In vivo precision is comparable to SAPPHIRE T1 mapping until middiastole (P > 0.07), but deteriorates in the later phases. CONCLUSIONS: The proposed sequence allows cardiac phase-resolved T1 mapping with integrated B1+ assessment at a temporal resolution of 40 ms. Magn Reson Med 79:2087-2100, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Real-time phase contrast magnetic resonance imaging for assessment of haemodynamics: from phantom to patients.

OBJECTIVES: Assessment of haemodynamics is crucial in many cardiac diseases. Phase contrast MRI (PC-MRI) can accurately access it. Arrhythmia is a major limitation in conventional segmented PC-MRI (SEG). A real-time PC-MRI sequence (RT) could overcome this. We validated RT by comparing to SEG. METHODS: A prototype RT using shared velocity encoding was tested against SEG at 1.5 T in a flow phantom and consecutively included patients with (n = 55) or without (n = 59) aortic valve disease. In patients with atrial fibrillation (Afib, n = 15), only RT was applied. Phantom: PC images were acquired in front of and behind an interchangeable aortic-stenosis-like inlay. Mean velocity and flow were quantified. PATIENTS: PC images were acquired in the ascending aorta, pulmonary trunk and superior caval vein. Peak velocity, stroke volume and regurgitant fraction were quantified. RESULTS: Phantom: Mean velocities (11 ± 1 to 207 ± 10 cm/s) and flow correlated closely between SEG and RT (r ≥ 0.99, ICC ≥ 0.98, p < 0.0005). Patients without AVD or with aortic regurgitation: Concordance of SEG and RT was excellent regarding peak velocities, stroke volumes (r ≥ 0.91, ICC ≥ 0.94, p < 0.0005) and regurgitant fractions (r = 0.95, ICC = 0.95, p < 0.0005). RT was feasible in all patients with Afib. CONCLUSIONS: The real-time sequence is accurate compared to conventional segmented PC-MRI. Its applicability in Afib was shown. Real-time PC-MRI might become a valuable tool in arrhythmia. KEY POINTS: • Assessment of haemodynamics is crucial in many cardiac diseases. • Arrhythmias are a major limitation of conventional techniques in cardiac magnetic resonance. • A real-time technique, which allows application in arrhythmia, was validated. • This real-time technique might become a valuable tool in arrhythmic patients.

Rapid parametric mapping of the longitudinal relaxation time T1 using two-dimensional variable flip angle magnetic resonance imaging at 1.5 Tesla, 3 Tesla, and 7 Tesla.

INTRODUCTION: Visual but subjective reading of longitudinal relaxation time (T1) weighted magnetic resonance images is commonly used for the detection of brain pathologies. For this non-quantitative measure, diagnostic quality depends on hardware configuration, imaging parameters, radio frequency transmission field (B1+) uniformity, as well as observer experience. Parametric quantification of the tissue T1 relaxation parameter offsets the propensity for these effects, but is typically time consuming. For this reason, this study examines the feasibility of rapid 2D T1 quantification using a variable flip angles (VFA) approach at magnetic field strengths of 1.5 Tesla, 3 Tesla, and 7 Tesla. These efforts include validation in phantom experiments and application for brain T1 mapping. METHODS: T1 quantification included simulations of the Bloch equations to correct for slice profile imperfections, and a correction for B1+. Fast gradient echo acquisitions were conducted using three adjusted flip angles for the proposed T1 quantification approach that was benchmarked against slice profile uncorrected 2D VFA and an inversion-recovery spin-echo based reference method. Brain T1 mapping was performed in six healthy subjects, one multiple sclerosis patient, and one stroke patient. RESULTS: Phantom experiments showed a mean T1 estimation error of (-63±1.5)% for slice profile uncorrected 2D VFA and (0.2±1.4)% for the proposed approach compared to the reference method. Scan time for single slice T1 mapping including B1+ mapping could be reduced to 5 seconds using an in-plane resolution of (2×2) mm2, which equals a scan time reduction of more than 99% compared to the reference method. CONCLUSION: Our results demonstrate that rapid 2D T1 quantification using a variable flip angle approach is feasible at 1.5T/3T/7T. It represents a valuable alternative for rapid T1 mapping due to the gain in speed versus conventional approaches. This progress may serve to enhance the capabilities of parametric MR based lesion detection and brain tissue characterization.

Assessment of nonischemic fibrosis in hypertrophic cardiomyopathy: comparison of gadopentetate dimeglumine and gadobenate dimeglumine for enhanced cardiovascular magnetic resonance imaging.

PURPOSE: To compare whether the higher relaxivity contrast agent gadobenate is superior for the identification of nonischemic late gadolinium enhancement (LGE) in hypertrophic cardiomyopathy (HCM) compared to standard relaxivity agents such as gadopentetate. MATERIALS AND METHODS: Fifteen patients with HCM and positive LGE based on routine cardiac magnetic resonance (CMR) with 0.2 mmol/kg gadopentetate were enrolled. Each patient thereafter underwent a second enhanced CMR exam with 0.2 mmol/kg gadobenate using the same CMR protocol. LGE was assessed in a short axis stack acquired after contrast administration using an inversion recovery gradient echo sequence. Two independent blinded readers quantified LGE by manual planimetry. The signal intensities of injured myocardium, remote myocardium, left ventricular cavity, and air were measured in identical locations using anatomical landmarks and dedicated software. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. RESULTS: No adverse events related to contrast administration occurred. Gadobenate dimeglumine showed a higher SNR of injured myocardium (45.4 ± 24.0 vs. 31.1 ± 16.6, P = 0.002) and a higher CNR between remote and injured myocardium (37.6 ± 25.0 vs. 26.5 ± 17.6, P = 0.006) compared to gadopentetate dimeglumine. The amount of LGE (based on the same postprocessing criteria and definitions) was higher with gadobenate dimeglumine (12.7 ± 8.5 g vs. 9.4 ± 5.6 g, P = 0.005). There was no difference in intra- and interobserver variability between gadopentetate dimeglumine and gadobenate dimeglumine. CONCLUSION: CMR with the high relaxivity contrast agent gadobenate dimeglumine reveals significantly more tissue with LGE in patients with HCM.

Assessment of the right ventricle with cardiovascular magnetic resonance at 7 Tesla.

BACKGROUND: Functional and morphologic assessment of the right ventricle (RV) is of clinical importance. Cardiovascular magnetic resonance (CMR) at 1.5T has become gold standard for RV chamber quantification and assessment of even small wall motion abnormalities, but tissue analysis is still hampered by limited spatial resolution. CMR at 7T promises increased resolution, but is technically challenging. We examined the feasibility of cine imaging at 7T to assess the RV. METHODS: Nine healthy volunteers underwent CMR at 7T using a 16-element TX/RX coil and acoustic cardiac gating. 1.5T served as gold standard. At 1.5T, steady-state free-precession (SSFP) cine imaging with voxel size (1.2 x 1.2 x 6) mm3 was used; at 7T, fast gradient echo (FGRE) with voxel size (1.2 x 1.2 x 6) mm3 and (1.3 x 1.3 x 4) mm3 were applied. RV dimensions (RVEDV, RVESV), RV mass (RVM) and RV function (RVEF) were quantified in transverse slices. Overall image quality, image contrast and image homogeneity were assessed in transverse and sagittal views. RESULTS: All scans provided diagnostic image quality. Overall image quality and image contrast of transverse RV views were rated equally for SSFP at 1.5T and FGRE at 7T with voxel size (1.3 x 1.3 x 4)mm3. FGRE at 7T provided significantly lower image homogeneity compared to SSFP at 1.5T. RVEDV, RVESV, RVEF and RVM did not differ significantly and agreed close between SSFP at 1.5T and FGRE at 7T (p=0.5850; p=0.5462; p=0.2789; p=0.0743). FGRE at 7T with voxel size (1.3 x 1.3 x 4) mm3 tended to overestimate RV volumes compared to SSFP at 1.5T (mean difference of RVEDV 8.2 ± 9.3 ml) and to FGRE at 7T with voxel size (1.2 x 1.2 x 6) mm3 (mean difference of RVEDV 9.3 ± 8.6 ml). CONCLUSIONS: FGRE cine imaging of the RV at 7T was feasible and provided good image quality. RV dimensions and function were comparable to SSFP at 1.5T as gold standard.

Cost evaluation of cardiovascular magnetic resonance versus coronary angiography for the diagnostic work-up of coronary artery disease: application of the European Cardiovascular Magnetic Resonance registry data to the German, United Kingdom, Swiss, and United States health care systems.

BACKGROUND: Cardiovascular magnetic resonance (CMR) has favorable characteristics for diagnostic evaluation and risk stratification of patients with known or suspected CAD. CMR utilization in CAD detection is growing fast. However, data on its cost-effectiveness are scarce. The goal of this study is to compare the costs of two strategies for detection of significant coronary artery stenoses in patients with suspected coronary artery disease (CAD): 1) Performing CMR first to assess myocardial ischemia and/or infarct scar before referring positive patients (defined as presence of ischemia and/or infarct scar to coronary angiography (CXA) versus 2) a hypothetical CXA performed in all patients as a single test to detect CAD. METHODS: A subgroup of the European CMR pilot registry was used including 2,717 consecutive patients who underwent stress-CMR. From these patients, 21% were positive for CAD (ischemia and/or infarct scar), 73% negative, and 6% uncertain and underwent additional testing. The diagnostic costs were evaluated using invoicing costs of each test performed. Costs analysis was performed from a health care payer perspective in German, United Kingdom, Swiss, and United States health care settings. RESULTS: In the public sectors of the German, United Kingdom, and Swiss health care systems, cost savings from the CMR-driven strategy were 50%, 25% and 23%, respectively, versus outpatient CXA. If CXA was carried out as an inpatient procedure, cost savings were 46%, 50% and 48%, respectively. In the United States context, cost savings were 51% when compared with inpatient CXA, but higher for CMR by 8% versus outpatient CXA. CONCLUSION: This analysis suggests that from an economic perspective, the use of CMR should be encouraged as a management option for patients with suspected CAD.

Complementary assessment of aortic bioprosthetic dysfunction using cardiac magnetic resonance imaging and computed tomography.

The case is reported of a 28-year-old subject with a bioprosthesis (Shelhigh 31) in the aortic position, with symptoms of heart failure and possible prosthetic dysfunction. As the echocardiographic interrogation remained inconclusive, the patient underwent cardiovascular magnetic resonance (CMR) imaging, which revealed an impaired movement of the non-coronary cusp. In addition, computed tomography (CT) demonstrated severe calcification of the immobile prosthetic component. Hence, in selected patients, both CMR and CT can be used as complementary tools to evaluate the dysfunction and pathology of heart valve bioprostheses.

In vitro assessment of heart valve bioprostheses by cardiovascular magnetic resonance: four-dimensional mapping of flow patterns and orifice area planimetry.

OBJECTIVE: The hemodynamics in proximity to stented aortic bioprostheses still differ from that under physiological conditions. This may prevent desired cardiac remodeling and promote aortic diseases. Further improvements in prosthetic technology require an accurate survey of the flow conditions on the prosthetic level and in the ascending aorta. Cardiovascular magnetic resonance (CMR) may have the potential to provide more information by determining the prosthetic orifice area and visualizing the intravascular flow dynamics. We tested the feasibility to better characterize the hemodynamics of various stented bioprostheses in a pulsatile flow phantom by using CMR. METHODS: The custom-made model consisting of a commercially available pump generating pulsatile flow, a tube system filled with a glycerin-water mixture, and a handcrafted bulbar-shaped cylinder holding the bioprostheses and simulating the aortic root, was located in a clinical 1.5T CMR system. In this study, 10 stented aortic bioprostheses were investigated (Perimount® 21, 23; Mitroflow® 19, 25; Hancock® 21, 23, 25; Mosaic® 21; Epic Supra® 21, 23). The prosthetic orifice area was visualized using steady-state free-precession cine imaging (spatial/temporal resolution 1.3×1.3×5 mm³/29 ms), quantified by manual planimetry and compared with published transthoracic echocardiographic data. Time-resolved three-dimensional phase-contrast flow mapping (1.8×1.8×3 mm³/45 ms) was applied to analyze the transprosthetic flow pattern. RESULTS: Visualization of the prosthetic orifice area and the transprosthetic flow pattern was feasible in all prostheses. All orifice areas obtained by CMR in vitro were within one standard deviation of the mean of the published reference values obtained by echocardiography in vivo. Turbulent flow with vortex formation occurred both in proximity to the prosthesis and on the 'ascending aortic' level. Larger prosthetic sizes led to decreased flow velocities, but not mandatorily to less turbulences. CONCLUSIONS: CMR allowed for a detailed interrogation of the fluid dynamics of various heart valve bioprostheses in a pulsatile flow model. It is an attractive tool to define proprietary reference values of the orifice area under standardized conditions and provides novel information regarding the flow pattern in proximity to the prosthesis.

Assessment of mitral bioprostheses using cardiovascular magnetic resonance.

BACKGROUND: The orifice area of mitral bioprostheses provides important information regarding their hemodynamic performance. It is usually calculated by transthoracic echocardiography (TTE), however, accurate and reproducible determination may be challenging. Cardiovascular magnetic resonance (CMR) has been proven as an accurate alternative for assessing aortic bioprostheses. However, whether CMR can be similarly applied for bioprostheses in the mitral position, particularly in the presence of frequently coincident arrhythmias, is unclear. The aim of the study is to test the feasibility of CMR to evaluate the orifice area of mitral bioprostheses. METHODS: CMR planimetry was performed in 18 consecutive patients with mitral bioprostheses (n = 13 Hancock(R), n = 4 Labcore(R), n = 1 Perimount(R); mean time since implantation 4.5 +/- 3.9 years) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5T MR system. CMR results were compared with pressure half-time derived orifice areas obtained by TTE. RESULTS: Six subjects were in sinus rhythm, 11 in atrial fibrillation, and 1 exhibited frequent ventricular extrasystoles. CMR image quality was rated as good in 10, moderate in 6, and significantly impaired in 2 subjects. In one prosthetic type (Perimount(R)), strong stent artifacts occurred. Orifice areas by CMR (mean 2.1 +/- 0.3 cm2) and TTE (mean 2.1 +/- 0.3 cm2) correlated significantly (r = 0.94; p < 0.001). Bland-Altman analysis showed a 95% confidence interval from -0.16 to 0.28 cm2 (mean difference 0.06 +/- 0.11 cm2; range -0.1 to 0.3 cm2). Intra- and inter-observer variabilities of CMR planimetry were 4.5 +/- 2.9% and 7.9 +/- 5.2%. CONCLUSIONS: The assessment of mitral bioprostheses using CMR is feasible even in those with arrhythmias, providing orifice areas with close agreement to echocardiography and low observer dependency. Larger samples with a greater variety of prosthetic types and more cases of prosthetic dysfunction are required to confirm these preliminary results.

Comparison of left ventricular function assessment using phonocardiogram- and electrocardiogram-triggered 2D SSFP CINE MR imaging at 1.5 T and 3.0 T.

OBJECTIVE: As high-field cardiac MRI (CMR) becomes more widespread the propensity of ECG to interference from electromagnetic fields (EMF) and to magneto-hydrodynamic (MHD) effects increases and with it the motivation for a CMR triggering alternative. This study explores the suitability of acoustic cardiac triggering (ACT) for left ventricular (LV) function assessment in healthy subjects (n = 14). METHODS: Quantitative analysis of 2D CINE steady-state free precession (SSFP) images was conducted to compare ACT's performance with vector ECG (VCG). Endocardial border sharpness (EBS) was examined paralleled by quantitative LV function assessment. RESULTS: Unlike VCG, ACT provided signal traces free of interference from EMF or MHD effects. In the case of correct R-wave recognition, VCG-triggered 2D CINE SSFP was immune to cardiac motion effects-even at 3.0 T. However, VCG-triggered 2D SSFP CINE imaging was prone to cardiac motion and EBS degradation if R-wave misregistration occurred. ACT-triggered acquisitions yielded LV parameters (end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and left ventricular mass (LVM)) comparable with those derived from VCG-triggered acquisitions (1.5 T: ESV(VCG) = (56 +/- 17) ml, EDV(VCG) = (151 +/- 32) ml, LVM(VCG) = (97 +/- 27) g, SV(VCG) = (94 +/- 19) ml, EF(VCG) = (63 +/- 5)% cf. ESV(ACT) = (56 +/- 18) ml, EDV(ACT) = (147 +/- 36) ml, LVM(ACT) = (102 +/- 29) g, SV(ACT) = (91 +/- 22) ml, EF(ACT) = (62 +/- 6)%; 3.0 T: ESV(VCG) = (55 +/- 21) ml, EDV(VCG) = (151 +/- 32) ml, LVM(VCG) = (101 +/- 27) g, SV(VCG) = (96 +/- 15) ml, EF(VCG) = (65 +/- 7)% cf. ESV(ACT) = (54 +/- 20) ml, EDV(ACT) = (146 +/- 35) ml, LVM(ACT) = (101 +/- 30) g, SV(ACT) = (92 +/- 17) ml, EF(ACT) = (64 +/- 6)%). CONCLUSIONS: ACT's intrinsic insensitivity to interference from electromagnetic fields renders it suitable for clinical CMR.