Histogram Analysis of Native T 1 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.
(© 2018 International Society for Magnetic Resonance in Medicine.)