Diffusion tensor cardiovascular magnetic resonance differentiates pediatric dilated and hypertrophic cardiomyopathies

Pediatric cardiomyopathies represent a heterogeneous group of myocardial diseases with significant morbidity and mortality. Conventional cardiovascular magnetic resonance (CMR) techniques provide functional and tissue characterization but offer limited insight into myocardial microstructural organization. Diffusion tensor imaging (DTI) enables non-invasive assessment of myocardial microstructure through quantitative metrics such as apparent diffusion coefficient (ADC) and fractional anisotropy (FA). This study aims to evaluate the utility of DTI in differentiating dilated and hypertrophic cardiomyopathies in pediatric patients through quantitative analysis of ADC and FA, hypothesizing that these metrics provide distinct microstructural biomarkers that correlate with ventricular function.

This study employed a mixed retrospective-prospective design and included 21 pediatric patients (0-18 years) with confirmed cardiomyopathies (12 dilated, 9 hypertrophic) and 11 healthy volunteers. Cardiac DTI was performed on a 3 T MRI system using a free-breathing, motion-compensated protocol. Quantitative analysis of ADC and FA was conducted in the interventricular septum. Group comparisons were performed using non-parametric statistical tests, correlations with left ventricular ejection fraction (LVEF) were assessed using Spearman analysis, and receiver operating characteristic (ROC) curves were generated to evaluate discriminatory performance.

Significant differences were observed in ADC (H = 24.50, p < 0.001) and FA (H = 15.31, p < 0.001) among groups. Dilated cardiomyopathy (DCM) demonstrated the highest ADC values (0.068 ± 0.013 mm²/s) and the lowest FA (0.413 ± 0.058), whereas hypertrophic cardiomyopathy (HCM) showed moderately elevated ADC (0.044 ± 0.005 mm²/s) with preserved FA (0.527 ± 0.029), not significantly different from healthy volunteers. ADC correlated inversely with LVEF (ρ =  - 0.409, p < 0.001), while FA showed a positive correlation (ρ = +0.443, p < 0.001), assessed in patients with complete LVEF data (n = 18). ROC analysis demonstrated excellent discriminatory performance for ADC in DCM identification (AUC = 1.000) and good performance for FA in both DCM (AUC = 0.912) and HCM identification (AUC = 0.813).

Cardiac DTI-derived metrics reveal distinct microstructural patterns in pediatric cardiomyopathies and show significant associations with ventricular function. These findings suggest that DTI may provide complementary quantitative biomarkers for myocardial characterization in pediatric populations, warranting further validation in prospective and multicenter studies.