of atrophy (tissue loss), which can be both global (e.g., thinning of the cortex in aging)9 and local (e.g., reduction of hippocampal volume in Alzheimer’s disease)10. The T2 data (Fig 1b,d) is a FLAIR (fluid-attenuated inversion recovery) acquisition that also depicts basic anatomy, but is valuable primarily for detection of focal “hyperintensities” (i.e., high-signal regions) in white matter. T2 hyperintensities represent white matter lesions that have been associated with a broad range of neuropathological conditions11 (e.g., small vessel ischaemic disease), as well as occurring with increasing incidence in aging populations without (or potentially before) manifestation of neurological symptoms. IDPs relating to the volume of these white matter lesions will be included in future data releases. swMRI is a flexible modality that can be processed in multiple ways, each sensitive to different clinically-relevant properties. The first data release includes T2* signal decay times and enhancement of venous vasculature using susceptibility-weighted image (SWI) filtering12 (Fig 1e,f). swMRI IDPs in the current data release are the median T2* in each of 14 major subcortical gray matter structures, for example reflecting increased iron deposition associated with neurodegeneration13.
