Multimodal MRI Acquisition and Preprocessing

MRI data were collected on a GE Discovery MR 750 3.0T system using an 8-channel head coil. Diffusion was measured with a multi-shell EPI sequence encoded for 45 non-collinear diffusion directions, (15 unique directions at each of 3 b-values: 500, 1500, and 4000 s/mm²) and 2 at b = 0 s/mm² (in-plane resolution = 1.875 × 1.875 mm, thickness = 2.5 mm, TR = 7 s, TE = 87.4 ms, flip = 90°). An anatomical T1-weighted fast spoiled gradient echo (FSPGR) scan (1 mm³, TR = 8.108 s, TE = 3.172 ms, flip = 8°) was also acquired. Preprocessing of diffusion data was performed using in-house software and included eddy current correction (Zhuang et al., 2006 (link)), rigid body correction for motion with corresponding adjustments to the vector matrix, correction of susceptibility-induced field distortions (Holland et al., 2010 (link)), and correction for gradient non-linearities (Jovicich et al., 2006 (link)).