In vivo cardiac diffusion tensor imaging quantifies microstructural disorganization to distinguish hypertrophic cardiomyopathy from hypertensive heart disease.

OBJECTIVES: To evaluate whether cardiac diffusion tensor imaging (cDTI) can discriminate hypertrophic cardiomyopathy (HCM) from hypertensive heart disease (HHD) based on microstructural alterations.

MATERIALS AND METHODS: This prospective study enrolled 40 HCM patients and 14 HHD patients who underwent 3.0T cardiac magnetic resonance (CMR), including cDTI, T1 mapping and late gadolinium enhancement (LGE). Parameters of cDTI (mean diffusivity [MD], secondary eigenvector [E2A], helix angel [HA)] and fractional anisotropy [FA]) were compared across groups using analysis of covariance. Diagnostic performance was assessed using receiver operating characteristic analysis. A subgroup analysis was performed in HCM patients with mild hypertrophy (left ventricular wall thickness [LVWT] 13-19 mm).

RESULTS: Compared to patients with HHD, those with HCM showed significantly greater LVWT, LGE extent, native T1 and extracellular volume fraction (ECV, all p < 0.05). cDTI revealed significant microstructural alterations in HCM, characterized by reduced FA (p = 0.001) and elevated E2A p < 0.001). Analysis of covariance confirmed these differences after adjusting for LVWT, native T1, and ECV. ROC analysis demonstrated that E2A (AUC = 0.88) and FA (AUC = 0.79) had superior diagnostic performance for distinguishing HCM from HHD, outperforming native T1 (AUC = 0.76), ECV (AUC = 0.75), and LGE extent (AUC = 0.67). In the HCM subgroup, E2A maintained the highest diagnostic performance (AUC = 0.86), followed by FA and ECV (both AUC = 0.73).

CONCLUSIONS: E2A and FA derived from cDTI were robust biomarkers of microstructural alterations, enabling superior differentiation of HCM from HHD beyond conventional hypertrophy and fibrosis indices. These findings support the potential utility of cDTI in diagnosis of ambiguous hypertrophy.