(A) Tomographic DSI reconstruction of an infarcted rat heart. The basal portion of the infarct and the adjacent border zones are shown. Myofiber architecture is relatively preserved in the border zones but is severely perturbed in the infarct. Numerous residual myofibers are present within the septal and basal portions of the infarct. The residual myofibers in the infarct resemble subendocardial (pink) and subepicardial (green) myofiber tracts, and make contact with/intersect each other in a mesh-like structure. The dashed white arrow marks the location of a node of orthogonal myofiber contact, which is shown in more detail in panel (B). (B) Magnified view of a node of orthogonal myofiber intersection or contact (NOMIC). (C) Hematoxylin and eosin stain (20×) of the NOMIC showing longitudinally-oriented myofibers intersecting with transversely-oriented myofibers, confirming the DSI findings. The arrows in panels (B, C) point to the area of myofiber intersection/contact. (C, D) The majority of the infarct is infiltrated with scar tissue (darker purple in color). The residual myofibers (bright pink) appear highly organized and show the striations characteristic of cardiomyocytes (panel D, 400×). Reproduced with permission from Sosnovik et al .