FIG 6. Schematic representation of the ellipsoid that describes the mean diffusion of a water molecule at the center of a voxel in all directions. The eigenvalues of the diagonalized diffusion tensor (
1, 2, 3) are the axes of this ellipsoid. Also represented is a sphere with a radius that is the average value of the three axes of the corresponding ellipsoid. The volume ratio used is the ratio of the volume of the ellipsoid to the volume of the sphere, as discussed in the Appendix and in reference 13. The anisotropy index used in this investigation was as follows: 1 - volume ratio.
