Fig. 1.

Region of interest selection for diffusion tensor tractography at pons, posterior limb of internal capsule and precentral gyrus.

A. Region of interest for pons was selected at expected corticopinal tract area on diffusion tensor MR imaging color map. Left side is left.

B. Region of interest for corticospinal tract was selecteed at lateral half of posterior limb of internal capsule on diffusion tensor MR imaging color map.

C. Precentral gyrus was determined by fibers crossing pons and posterior limb of internal capsule regions of interest, and it was identified by using anatomical landmarks such as posterior knob and superior frontal and precentral sulci on a B0 image.

D. Four precentral gyrus regions of interest were drawn from medial (ROI 1) to lateral precentral gyrus (ROI 4) on B0 image. ROI 3 and ROI 4 were drawn near to posterior knob of precentral gyrus.