CSF fraction measured by MR T2 relaxometry is better than PVS load to associate with amyloid beta deposition in 11C-PiB PET

Motivation: Perivascular space (PVS) enlargement is used to estimate the severity of glymphatic clearance dysfunction in Alzheimer’s disease. There is a lack of imaging tool to estimate the cerebral cortical PVS load. Goal(s): Investigate the association between the MR T2-relaxometry based CSF fraction (CSFF), a measure of total PVS (including both MR visible and invisible PVS), and PET imaging based Aβ deposition. Approach: Use 6-echo FAST-T2 image to map CSFF and correlate it with Aβ deposition in both cognitive normal and mild cognitive impaired groups. Results: CSFF is better than PVS load in association with Aβ deposition in MCI/AD subjects. Impact: Parenchymal CSF fraction measured using MR T2-relaxometry is an estimate of total perivascular space, which reflect glymphatic clearance function. It has superior performance in correlation with Aβ deposition than MRI based PVS segmentation.