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

Background The use of native T 1 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 T 1 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, 10 th /25 th /50 th /75 th /90 th percentiles, maximums, kurtosis, entropy, and lower SD and energy of T 1 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, 10 th /25 th /50 th /75 th /90 th percentiles, maximum, entropy, and lower energy of T 1 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 T 1 mapping provide more information than mean T 1 times alone. Among these parameters, entropy and energy may correlate better with LVWT, myocardial late gadolinium enhancement, and strain parameters than mean T 1 times in HCM patients. Level of Evidence : 2 Technical Efficacy Stage : 2 J. Magn. Reson. Imaging 2019;49:668–677.