average atrophy map (mean jacobian) in 32 patients with Alzheimer's disease

Contributed by relajoie on May 11, 2018

Collection: Prospective longitudinal atrophy in Alzheimer’s disease correlates with the intensity and topography of baseline tau-PET

Description: 2 MPRAGE-MRI were available for each of the 32 cognitively impaired patients with Alzheimer's disease (MCI or dementia stage) included in the analyses. MRIs were preprocessed using SPM12 pairwise longitudinal MRI pipeline to create an average timepoint MRI and create a jacobian map representing the local changes between the baseline and follow up scans. Jacobian maps were multiplied by the gray matter segmentation of the average midpoint MRI, to focus on GM changes, and warped to MNI template space. All 32 warped, GM-jacobian maps were averaged across patients, and smoothed within a template cortical GM mask using AFNI 3dBlurInMask. The applied smoothness was 8mm FWHM to reach a final resolution of ~8mm isotropic (to be comparable to PET, see other images from Figure 1a) Finally, the values were reversed so that higher values represent higher rates of atrophy over time to simplify visualization.