3.

Fiber density measure derived from microCT fODFS. (a-c) Representative FD slices showing contrast between gray and white matter. Scale bars are 1 mm. (d-f) Examples of microCT data from 150 μm³ cubic regions calculated as having (d) high (FD = 0.41), (e) medium (FD = 0.32), and (f) low (FD = 0.20) fiber density. Arrows in (f) indicate an example of a partial volume effect, where a small region with high fiber density (lower right) is present with a larger region with low fiber density (upper left), resulting in an overall low FD value.