Imperfect overlap of WM and GM mask, especially in in the lower thoracic and lumbar levels #32
Description
@Nilser3 noticed some issues with the GM mask PAM50_gm.nii.gz in version 6.5:
Issue 1: Mismatch between GM mask and T2* template
Issue 2: Slight mis-registration between the T2*w and the T2w template
Issue 3: Some pixels far away from the GM mask have non-zero values
