MR microscopy of cardiac microstructure with diffusion and structural tensor imaging in high-performance clinical and pre-clinical MR scanners

Motivation: Optical microscopy is limited to small tissue samples, lacking volumetric coverage to study the complex three-dimensional microstructure of the heart. Goal(s): To develop an approach for whole-heart MR microscopy of human samples in an ultrahigh performance clinical MRI scanner, with enhanced imaging of transmural samples in a preclinical MRI system. Approach: We introduce 3D TSE and GRE imaging protocols for whole-heart and transmural tissue samples and demonstrate the ability of this approach to depict microstructure through structural tensor analysis compared to high-resolution diffusion tensor analysis. Results: High-resolution 3D TSE and GRE data delivers non-destructive imaging of the heart at the mesoscopic scale. Impact: High-resolution 3D MR imaging of the heart, with each voxel containing a few tens of cells, can further our understanding of cardiac microstructure in health and disease. These advances pave the way for non-destructive whole-heart MR microscopy in large samples.