To this end, pre-MRS FSE images were aligned with the post-MRS localizer by rigid image registration. In the absence of motion, the resulting image-to-image coordinate transformation would be identical to the ideal transformation, which was determined from the scanner image coordinates as recorded in the DICOM image files. The deviation of the actual from the ideal transformation (i.e., the difference transformation) represents subject motion between the FSE used for voxel prescription and the post-MRS localizer scan.
