Fig. 4. a.
Atlases of the group means for FA, restricted volume fraction (fr) and apparent axon diameter index (a) for different tract ROIs derived from the ICBM-DTI-81 white matter atlas. A striking feature in the map of fr lies in the relatively uniform distribution throughout the whole brain cerebral white matter regardless of crossing structures, in distinction to that of FA. The slice number (i.e., first slice counted as slice 0) of the template FA in the ICBM space was labeled on each individual map.