Figure 8.

Tractography-histopathology analysis of axonal injury within the fornix (Fx) hemorrhage. (A) Right anterior oblique view of gross pathological specimen showing Fx hemorrhage (tip of metal probe). (B) Right lateral zoomed view of fiber tracts generated using the Fx hemorrhage as a seed region of interest, which is rendered as a 3-dimensional semitransparent object (red, Hem). Tracts passing through the Fx hemorrhage are color-coded according to their direction (green, anterior-posterior; blue, superior-inferior; red, medial-lateral). (C) Hematoxylin and eosin (H&E) stain of the Fx hemorrhage demonstrates longitudinal axonal segments (arrowheads) that pass through hemorrhage. Red blood cells are stained dark pink and are seen intercalating between the axons, rather than destroying the tissue completely. (D) The center of the hemorrhage is seen from within the hemorrhage itself, with neuroanatomic planes labeled as S (superior), I (inferior), P (posterior), and M (medial). The center of the grey axis bars within the hemorrhage corresponds to the center of the yellow axes shown in the inset (sagittal diffusion-weighted image at the midline). The arrow in (D) shows the blue fiber tracts indicated by the arrow in (B). In (B), these fiber tracts are seen from outside the hemorrhage, whereas in (D) these tracts are seen from within the hemorrhage. Fiber tracts in (D) are seen passing within 1.5 mm of the center of the hemorrhage.