For each subject, the skull-stripped baseline and follow-up SPGR images were each registered to the SPGR channel of the SRI24 atlas (Rohlfing et al., 2010) (http://nitrc.org/projects/sri24) via nonrigid image registration (Rohlfing and Maurer, 2003). We chose the SRI24 atlas over other available brain templates (e.g., MNI152) because of its ability to discern detailed anatomical structures, which can thus be unambiguously outlined directly in the atlas images without the need to access the images that were used to create the atlas itself. Independent cortical and subcortical parcellation maps for baseline and follow-up images were obtained by reformatting labels maps defined in SRI24 directly into baseline and follow-up SPGR image spaces using the subject-to-atlas coordinate transformations.
