Fig. 1.

Method for Defining Regions of Interest (ROIs).

1. High contrast structural images were coregistered to the 40-direction DWI data. 2. The putamen ROI (blue, upper left) was outlined on sequential T1-weighted axial images extending from top of lateral ventricles to the anterior commissure. 3. The substantia nigra (SN) ROI (red, lower left) was outlined on axial FLAIR images from the level of the red nucleus to superior cerebellar peduncle. 4. The putamen and SN ROIs were inspected and revised against the 40-direction FA maps (center). 5. Putamen and SN ROIs were coregistered to the 60-direction DWI data (right) and visually inspected against the 60-direction FA map.