Figure 3

Derivation of the tractographic coherence index (TCI) . The determination of the TCI is based on the maximum, median, and minimum HA classifications of myofibers within a ROI. This classification is depicted for myofibers in the midmyocardium (f _mid ). The maximum, median, and minimum HA curves are derived by averaging each HA classification successively in the base-apex and anterior-posterior directions of the ROI at each voxel. This creates the 3 transmural HA curves. The generated curves describe the transmural gradients in the maximum, median, and minimum myofiber HA, and are derived with fiber length limited to πR or the ROI. In the midmyocardium and subepicardium, the curves lie close to each other, consistent with highly coherent tracts, whereas in the subendocardium, tract coherence is lost due to the effect of the papillary muscles and trabeculations.