Voxel-scale diffusion tensor phenomapping of the healthy and pressure-overloaded human heart.

Summary

The study developed a free-breathing, submillimetre cardiac diffusion tensor MRI method that permits voxel-level characterization of myocardial microstructure. In healthy volunteers and patients with severe aortic stenosis, the method identified four microstructural classes and showed that pressure overload preserved cardiomyocyte spatial organization despite marked hypertrophy. Ex vivo and histological validation supported the imaging findings.

Key Findings

• A free-breathing submillimetre cardiac diffusion tensor imaging method enabled voxel-level assessment of myocardial microstructure.
• Four data-driven microstructural classes were identified in both healthy and pressure-overloaded hearts.
• Severe aortic stenosis with marked hypertrophy was associated with preserved cardiomyocyte spatial organization.

Clinical Implications

The technique could eventually improve phenotyping of hypertrophic and pressure-overload cardiomyopathies, support earlier detection of maladaptive remodelling, and provide imaging biomarkers for therapeutic trials. Clinical implementation will require larger validation studies, standardized acquisition, and assessment of prognostic value.

Limitations

• The provided abstract does not report the exact numbers of healthy volunteers and patients with aortic stenosis.
• The study establishes imaging feasibility and microstructural associations, but does not yet demonstrate prospective prognostic or treatment-guiding utility.

Future Directions

Future studies should standardize acquisition and analysis, recruit larger longitudinal cohorts, determine reproducibility across scanners, and test whether voxel-scale microstructural phenotypes predict heart failure, arrhythmia, or response to pressure-unloading therapy.