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Background: Four‐dimensional‐flow cardiac MR (4DF‐MR) offers advantages in primary mitral regurgitation. The relationship between 4DF‐MR‐derived mitral regurgitant volume (MR‐Rvol) and the post‐operative left ventricular (LV) reverse remodeling has not yet been established. Purpose: To ascertain if the 4DF‐MR‐derived MR‐Rvol correlates with the LV reverse remodeling in primary mitral regurgitation. Study Type: Prospective, single‐center, two arm, interventional vs. nonintervention observational study. Population: Forty‐four patients (male N = 30; median age 68 [59–75]) with at least moderate primary mitral regurgitation; either awaiting mitral valve surgery (repair [MVr], replacement [MVR]) or undergoing "watchful waiting" (WW). Field Strength/Sequence: 5 T/Balanced steady‐state free precession (bSSFP) sequence/Phase contrast imaging/Multishot echo‐planar imaging pulse sequence (five shots). Assessment: Patients underwent transthoracic echocardiography (TTE), phase‐contrast MR (PMRI), 4DF‐MR and 6‐minute walk test (6MWT) at baseline, and a follow‐up PMRI and 6MWT at 6 months. MR‐Rvol was quantified by PMRI, 4DF‐MR, and TTE by one observer. The pre‐operative MR‐Rvol was correlated with the post‐operative decrease in the LV end‐diastolic volume index (LVEDVi). Statistical Tests: Included Student t‐test/Mann–Whitney test/Fisher's exact test, Bland–Altman plots, linear regression analysis and receiver operating characteristic curves. Statistical significance was defined as P < 0.05. Results: While Bland–Altman plots demonstrated similar bias between all the modalities, the limits of agreement were narrower between 4DF‐MR and PMRI (bias 15; limits of agreement −36 mL to 65 mL), than between 4DF‐MR and TTE (bias −8; limits of agreement −106 mL to 90 mL) and PMRI and TTE (bias −23; limits of agreement −105 mL to 59 mL). Linear regression analysis demonstrated a significant association between the MR‐Rvol and the post‐operative decrease in the LVEDVi, when the MR‐Rvol was quantified by PMRI and 4DF‐MR, but not by TTE (P = 0.73). 4DF‐MR demonstrated the best diagnostic performance for reduction in the post‐operative LVEDVi with the largest area under the curve (4DF‐MR 0.83; vs. PMRI 0.78; and TTE 0.51; P = 0.89). Data Conclusion: This study demonstrates the potential clinical utility of 4DF‐MR in the assessment of primary mitral regurgitation. Evidence Level: 2 Technical Efficacy: Stage 5 [ABSTRACT FROM AUTHOR]

Background: Determination of myocardial blood flow (MBF) with MRI is usually performed with dynamic contrast enhanced imaging (MBFDCE). MBF can also be determined from coronary sinus blood flow (MBFCS), which has the advantage of being a noncontrast technique. However, comparative studies of MBFDCE and MBFCS in large cohorts are lacking. Purpose: To compare MBFCS and MBFDCE in a large cohort. Study Type: Prospective, sequence‐comparison study. Population: 147 patients with type 2 diabetes mellitus (age: 56+/−12 years; 106 male; diabetes duration: 12.9+/−8.1 years), and 25 age‐matched controls. Field Strength/Sequences: 1.5 Tesla scanner. Saturation recovery sequence for MBFDCE vs. phase‐contrast gradient‐echo pulse sequence (free‐breathing) for MBFCS. Assessment: MBFDCE and MBFCS were determined at rest and during coronary dilatation achieved by administration of adenosine at 140 μg/kg/min. Myocardial perfusion reserve (MPR) was calculated as the stress/rest ratio of MBF values. Coronary sinus flow was determined twice in the same imaging session for repeatability assessment. Statistical Tests: Agreement between MBFDCE and MBFCS was assessed with Bland and Altman's technique. Repeatability was determined from single‐rater random intraclass and repeatability coefficients. Results: Rest and stress flows, including both MBFDCE and MBFCS values, ranged from 33 to 146 mL/min/100 g and 92 to 501 mL/min/100 g, respectively. Intraclass and repeatability coefficients for MBFCS were 0.95 (CI 0.90; 0.95) and 5 mL/min/100 g. In Bland–Altman analysis, mean bias at rest was –1.1 mL/min/100 g (CI −3.1; 0.9) with limits of agreement of −27 and 24.8 mL/min/100 g. Mean bias at stress was 6.3 mL/min/100 g (CI −1.1; 14.1) with limits of agreement of −86.9 and 99.9. Mean bias of MPR was 0.11 (CI: −0.02; 0.23) with limits of agreement of −1.43 and 1.64. Conclusion: MBF may be determined from coronary sinus blood flow, with acceptable bias, but relatively large limits of agreement, against the reference of MBFDCE. Level of Evidence: 1 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]

Background: Cardiac MRI is an important imaging tool in congenital cardiac disease, but its use has been limited in the neonatal population as general anesthesia has been needed for breath‐holding. Technological advances in four‐dimensional (4D) flow MRI have now made nonsedated free‐breathing acquisition protocols a viable clinical option, but the method requires prospective validation in neonates. Purpose: To test the feasibility of compressed sensing (CS) 4D flow MRI in the neonatal population and to compare with standard previously validated two‐dimensional (2D) phase‐contrast (PC) flow MRI. Study type: Prospective, cohort, image quality. Population: A total of 14 healthy neonates (median [range] age: 2.5 [0–80] days; 8 male). Field Strength and Sequence: Noncontrast 2D cine gradient echo sequence with through‐plane velocity encoding (PC) sequence and compressed sensing (CS) three‐dimensional (3D), time‐resolved, cine phase‐contrast MRI with 3D velocity‐encoding (4D flow MRI) at 3 T. Assessment: Aortic 2D PC, and aortic, pulmonary trunk and superior vena cava CS 4D flow MRI were acquired using the feed and wrap technique (nonsedated) and quantified using commercially available software. Aortic flow and peak velocity were compared between methods. Internal consistency of 4D flow MRI was determined by comparing mean forward flow of the main pulmonary artery (MPA) vs. the sum of left and right pulmonary artery flows (LPA and RPA) and by comparing mean ascending aorta forward flow (AAo) vs. the sum of superior vena cava (SVC) and descending aorta flows (DAo). Statistical Tests: Flow and peak‐velocity comparisons were assessed using paired t‐tests, with P < 0.05 considered significant, and Bland–Altman analysis. Interobserver and intraobserver agreement and internal consistency were analyzed by intraclass correlation co‐efficient (ICC). Results: There was no statistically significant difference between ascending aortic forward flow between 2D PC and CS 4D Flow MRI (P = 0.26) with a bias of 0.11 mL (−0.59 to 0.82 mL) nor peak velocity (P = 0.11), with a bias of −5 cm/sec and (−26 to 16 cm/sec). There was excellent interobserver and intraobserver agreement for each vessel (interobserver ICC: AAo 1.00; DAo 0.94, SVC 0.90, MPA 0.99, RPA 0.98, LPA 0.96; intraobserver ICC: AAo 1.00; DAo 0.99, SVC 0.98, MPA 1.00, RPA 1.00, LPA 0.99). Internal consistency measures showed excellent agreement for both mean forward flow of main pulmonary artery vs. the sum of left and right pulmonary arteries (ICC: 0.95) and mean ascending aorta forward flow vs. the sum of superior vena cava and descending aorta flows (ICC: 1.00). Conclusion: Sedation‐free neonatal feed and wrap MRI is well tolerated and feasible. CS 4D flow MRI quantification is similar to validated 2D PC free‐breathing imaging with excellent interobserver and intraobserver agreement. Evidence Level: 1 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Four‐dimensional (4D) flow magnetic resonance imaging (MRI) allows multidirectional quantification of blood flow in the heart and great vessels. Comparability of the technique to the current reference standards of flow assessment—two‐dimensional (2D) flow MRI and Doppler echocardiography—varies in the literature. Image acquisition parameters likely impact upon the accuracy and reproducibility of 4D flow MRI. We therefore sought to review the current literature on 4D flow MRI in the heart and great vessels, in comparison to 2D flow MRI, Doppler echocardiography, and invasive catheterization. Using a predefined search strategy and inclusion and exclusion criteria, the databases EMBASE and Medline were searched in January 2021 for peer‐reviewed research articles comparing cardiac 4D flow MRI to 2D flow MRI, Doppler echocardiography and/or invasive catheterization. The data from all relevant articles were assimilated and analyzed using Mann–Whitney U and chi χ2 test. Forty‐four manuscripts met the eligibility criteria and were included in the review. The review showed agreement of 4D flow MRI to the reference standard methods of flow assessment, particular in the measurement of peak velocity and stroke volume in 55% of manuscripts. The use of valve tracking significantly improves agreement between 4D flow MRI and the reference modalities (79% matching with the use of valve tracking vs. 50% without, P = 0.04). This review highlights that the impact of acquisition parameters on 4D flow MRI accuracy is multifactorial. It is therefore important that each center conducts its own quality assurance prior to using 4D flow MRI for clinical decision‐making. Level of Evidence: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Background: Hypertrophic cardiomyopathy (HCM) remains the commonest cause of sudden cardiac death among young athletes. Differentiating between physiologically adaptive left ventricular (LV) hypertrophy observed in athletes' hearts and pathological HCM remains challenging. By quantifying the diffusion of water molecules, diffusion tensor imaging (DTI) MRI allows voxelwise characterization of myocardial microstructure.Purpose: To explore microstructural differences between healthy volunteers, athletes, and HCM patients using DTI.Study Type: Prospective cohort.Population: Twenty healthy volunteers, 20 athletes, and 20 HCM patients.Field Strength/sequence: 3T/DTI spin echo.Assessment: In-house MatLab software was used to derive mean diffusivity (MD) and fractional anisotropy (FA) as markers of amplitude and anisotropy of the diffusion of water molecules, and secondary eigenvector angles (E2A)-reflecting the orientations of laminar sheetlets.Statistical Tests: Independent samples t-tests were used to detect statistical significance between any two cohorts. Analysis of variance was utilized for detecting the statistical difference between the three cohorts. Statistical tests were two-tailed. A result was considered statistically significant at P ≤ 0.05.Results: DTI markers were significantly different between HCM, athletes, and volunteers. HCM patients had significantly higher global MD and E2A, and significantly lower FA than athletes and volunteers. (MDHCM = 1.52 ± 0.06 × 10-3 mm2 /s, MDAthletes = 1.49 ± 0.03 × 10-3 mm2 /s, MDvolunteers = 1.47 ± 0.02 × 10-3 mm2 /s, P < 0.05; E2AHCM = 58.8 ± 4°, E2Aathletes = 47 ± 5°, E2Avolunteers = 38.5 ± 7°, P < 0.05; FAHCM = 0.30 ± 0.02, FAAthletes = 0.35 ± 0.02, FAvolunteers = 0.36 ± 0.03, P < 0.05). HCM patients had significantly higher E2A in their thickest segments compared to the remote (E2Athickest = 66.8 ± 7, E2Aremote = 51.2 ± 9, P < 0.05).Data Conclusion: DTI depicts an increase in amplitude and isotropy of diffusion in the myocardium of HCM compared to athletes and volunteers as reflected by increased MD and decreased FA values. While significantly higher E2A values in HCM and athletes reflect steeper configurations of the myocardial sheetlets than in volunteers, HCM patients demonstrated an eccentric rise in E2A in their thickest segments, while athletes demonstrated a concentric rise. Further studies are required to determine the diagnostic capabilities of DTI.Evidence Level: 1 TECHNICAL EFFICACY STAGE: 2. [ABSTRACT FROM AUTHOR]

Background: Late gadolinium enhancement (LGE) imaging is well validated for the diagnosis and quantification of myocardial infarction (MI). 2D LGE imaging involves multiple breath-holds for acquisition of short-axis slices to cover the left ventricle (LV). 3D LGE methods cover the LV in a single breath-hold; however, breath-hold duration is typically long with images susceptible to motion artifacts.Purpose/hypothesis: To assess a single breath-hold 3D mDIXON LGE pulse sequence for image quality and quantitation of MI.Study Type: Prospective.Population: Ninety- two patients with prior MI.Field Strength/sequence: 1.5T cardiac MRI protocol using both conventional 2D phase sensitive inversion recovery and 3D mDIXON LGE imaging 10 minutes following contrast administration in random order to avoid bias.Assessment: Data were analyzed qualitatively for image quality (three observers). Quantitative assessment of myocardial scar mass (full-width half-maximum), scar transmurality, and contrast-to-noise ratio measurements were performed. Time for 2D and 3D LGE imaging was recorded.Statistical Tests: Paired Student's t-test, Wilcoxon rank test, Cohen κ statistic, Pearson correlation, linear regression, and Bland-Altman analysis.Results: Image quality scores were comparable between 3D and 2D LGE (1.4 ± 0.6 vs. 1.3 ± 0.5; P = 0.162). 3D LGE was associated with greater scar tissue mass (3D: 18.9 ± 17.5 g vs. 2D: 17.8 ± 16.2 g P = 0.03), although this difference was less pronounced when scar tissue was expressed as %LV mass (3D: 13.4 ± 9.9% vs. 2D: 12.7 ± 9.5% P = 0.07). For 3D vs. 2D scar mass there was a strong and significant positive correlation; Bland-Altman analysis showed mean mass bias of 1.1 g (95% confidence interval [CI]: -5.7 to 7.9). Segmental level agreement of scar transmurality between 3D and 2D LGE at the clinical viability threshold of 50% transmurality was excellent (κ = 0.870). 3D image acquisition (15.6 ± 1.4 sec) was just 5% of time required for 2D images (311.6 ± 43.2 sec) P < 0.0001.Data Conclusion: Single breath-hold 3D mDIXON LGE imaging allows quantitative assessment of MI mass and transmurality, with comparable image quality, in vastly shorter overall acquisition time compared with standard 2D LGE imaging.Level Of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1437-1445. [ABSTRACT FROM AUTHOR]

Purpose Intramyocardial hemorrhage and area at risk are both prognostic markers in acute myocardial infarction (AMI). Myocardial T2 and T2* mapping have been used to detect such tissue changes at 1.5T but these techniques are challenging at 3.0T due to additional susceptibility variation. We studied T2 and T2* myocardial mapping techniques at 3.0T on a system employing B1 shimming and compared two different methods of B0 shimming. Materials and Methods Fifteen volunteers and six AMI patients were scanned on a 3T system. Volume and image-based (IB) B0 shimming techniques were implemented. Single breath-hold, multiecho gradient, and spin echo sequences were employed from which T2* and T2 maps were calculated. Results In volunteers, there was no significant difference in mean values obtained with volume or IB shimming for T2 mapping (39.1 ± 6.0 msec vs. 39.4 ± 6.1 msec; P > 0.05) or for T2* mapping (24.2 ± 6.7 msec vs. 24.1 ± 5.2 msec; P > 0.05). There were no significant regional differences in mean T2 values between septal, anterior, and posterior segments with either shimming technique (all P > 0.05); but there were significant regional differences in mean T2* values using volume shimming (27.8 ± 5.2 msec vs. 28.4 ± 5.8 msec vs. 15.9 ± 8.3 msec; P < 0.05)-but not with IB shimming (25.7 ± 5.4 msec vs. 25.3 ± 5.9 msec vs. 18.7 ± 4.6 msec; P > 0.05). Conclusion At 3.0T, cardiac T2 mapping is robust. Although T2* mapping is prone to more regional heterogeneity this can be reduced by using IB instead of conventional volume B0 shimming. J. Magn. Reson. Imaging 2015;41:1013-1020. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Purpose: To compare patients' perceived satisfaction and tolerance of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) myocardial perfusion imaging. Materials and Methods: A questionnaire was sent retrospectively to 41 patients who had undergone both SPECT and MRI myocardial perfusion scans at our institution. The questionnaire assessed SPECT and MRI separately, and in a separate section compared the tests directly. The answers were scored and analyzed for statistical significance by the use of Wilcoxon signed-ranks and chi2 tests. Results: Thirty-five completed questionnaires were returned. In a direct comparison, 12 patients (34%) preferred MRI overall, nine (26%) preferred SPECT, and 14 (40%) expressed no preference. The ratings for the overall comfort of the scans were similar, with a score of 5.8 for SPECT and 5.7 for MRI (on a scale of 1-10). More patients stated a preference for MRI on scan comfort, duration, and safety (no statistical significance), but it was less well rated than SPECT for space on the scanner (P = 0.008). Three patients (9%) stated that they would not have an MRI scan again, while two patients (6%) said they would not repeat a SPECT scan. Conclusion: MRI myocardial perfusion imaging represents an acceptable alternative to SPECT with respect to patient tolerance and satisfaction. [ABSTRACT FROM AUTHOR]