Diffusion-weighted imaging was acquired on a 1.5 T GE Signa MR scanner (GE Healthcare, USA) at the Institute of Psychiatry/Maudsley Hospital, King's College London. A total of 60 contiguous near-axial slices were acquired with no gap and the following parameters: isotropic voxels of 2.5 mm×2.5 mm×2.5 mm, reconstructed as 1.875 mm×1.875 mm×2.5 mm, with coverage of the whole head, peripherally-gated to the cardiac cycle, with an echo time of 107 ms, and effective repetition time of 15 R-R intervals; diffusion encoding gradients duration 17.3 ms, providing a maximum diffusion weighting of 1300 s/mm2 (Jones et al., 2002 (link)). At each slice location, 7 images with no diffusion gradient (i.e., b = 0 s/mm2) were acquired, together with 64 diffusion weighted images (1300 s/mm2) with gradient directions distributed evenly in space.
T1-weighted MR images were also collected. A total of 124 slices were acquired, with a matrix size of 256×256, slice thickness of 1.5 mm and slice gap of 0 mm. Images were acquired in coronal plane, with a spoiled gradient recalled pulse sequence (flip angle 35°, field of view 240 mm, echo time 5 ms, repetition time 35 ms).
T1-weighted MR images were also collected. A total of 124 slices were acquired, with a matrix size of 256×256, slice thickness of 1.5 mm and slice gap of 0 mm. Images were acquired in coronal plane, with a spoiled gradient recalled pulse sequence (flip angle 35°, field of view 240 mm, echo time 5 ms, repetition time 35 ms).