Evaluation of Local Microstructural Gradients in the Myocardium of Subjects with Severe Aortic Stenosis.

Motivation: Diffusion tensor imaging of the heart can be performed with sub-mm resolution. However, established metrics do not fully take advantage of this improved resolution. Goal(s): We aimed to determine whether local gradients in helix angle (HA) could be calculated and used to characterize the microstructural response of the heart to the load imposed by aortic stenosis. Approach: Voxel-wise maps of radial, circumferential, minimum and maximum HA gradients were generated. Results: The radial HA gradient was reduced in aortic stenosis, but microstructural coherence was well preserved in these patients despite a marked increase in the thickness of the myocardium. Impact: DTI of the heart with sub-mm in-plane resolution allows maps of local HA gradients to be generated, providing novel insights into the microstructure of the heart.