The frontal white matter voxel could be segmented into gray matter, white matter, and CSF compartments. Limited resolution, and therefore conspicuity, limited segmentation to CSF and tissue in the thalamus. To account for individual differences in metabolite concentrations in each voxel, the percent of tissue in the total voxel (about 80–98% for the frontal and 95–99% for thalamus) was used as a correction factor by dividing the metabolite value by the proportion of tissue or percent tissue*100, e.g., Glu/.95. This approach yields the concentration per tissue amount in each voxel.
