Histogram Analysis of Native T1 Mapping and Its Relationship to Left Ventricular Late Gadolinium Enhancement, Hypertrophy, and Segmental Myocardial Mechanics in Patients With Hypertrophic Cardiomyopathy: Histogram Analysis of Native T1 Mapping in HCM

BACKGROUND: The use of native T1 mapping for evaluation of hypertrophic cardiomyopathy (HCM) is being explored, and its combination with histogram analysis may benefit the accuracy of such assessments. PURPOSE: To investigate the relationship of segmental left ventricular wall thickness (LVWT), myocardial fibrosis, and strain parameters with segmental histogram parameters of native T1 mapping in HCM patients. STUDY TYPE: Retrospective. SUBJECTS: Ninety-three HCM patients without previous cardiovascular diseases were included. FIELD STRENGTH/SEQUENCE: 3.0T cardiac MR. Steady-state free precession cine imaging, modified Look-Locker inversion recovery, phase-sensitive inversion recovery. ASSESSMENT: Images were assessed by three experienced radiologists. STATISTICAL TESTS: Mann-Whitney U-tests, area under the curve (AUC), Spearman's rank correlation, intraclass correlation coefficient, and Bland-Altman test were used for statistical analysis. RESULTS: A higher LVWT value correlated with higher means, minimums, 10th /25th /50th /75th /90th percentiles, maximums, kurtosis, entropy, and lower SD and energy of T1 mapping (P < 0.05 for all), with the correlation being stronger for entropy and energy (Spearman's rho = 0.439 and -0.413, respectively) than other parameters. Late gadolinium enhancement positive (LGE+) segments exhibited higher mean, minimum, 10th /25th /50th /75th /90th percentiles, maximum, entropy, and lower energy of T1 times than late gadolinium enhancement negative (LGE-) segments (P < 0.001 for all). Impaired strain function parameters (peak thickening and thickening rate in radial, circumferential, and longitudinal directions) demonstrated a weak correlation with higher entropy (P < 0.001 for all) and lower energy (P < 0.001 for all). DATA CONCLUSION: Histogram parameters of native T1 mapping provide more information than mean T1 times alone. Among these parameters, entropy and energy may correlate better with LVWT, myocardial late gadolinium enhancement, and strain parameters than mean T1 times in HCM patients. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:668-677.