2.5.1. Voxel Placement and Check
MRS
The MRS voxel was 25 × 25 × 15 mm and covered the dACC. An in-house MATLAB (R2013b) script was applied to build a voxel image based on the location information on the head of MRS data. This voxel image indicates the location of the MRS voxel, when overlapping on the corresponding structural image at the same scan session. To check whether the location of the MRS voxel covered the target region, i.e., dACC at coordinates [0, 34, 26] in MNI (standard) space, individual structural images were co-registered to a MNI template, and the same transform matrix was applied on the corresponding voxel images. Finally, tissue segmentation was conducted at individual space to segment grey matter (GM), white matter (WM), and CSF. The volumetric proportion (percentage) of each tissue type within the MRS voxel was further calculated for partial volume correction and quality check (refer to 