T2 selective saturation labeling for imaging of water exchange between tissues and CSF.

Motivation: Water exchange between tissue and CSF may contribute to CSF production and glymphatic clearance. The large difference in T2 between tissue and fluid suggests T2 saturation transfer can be used to image this exchange. Goal(s): We aimed to develop a method for water exchange imaging using T2 saturation. Approach: A novel strategy to control for systematic errors from direct effects of T2 saturation on fluid is proposed and evaluated in healthy volunteers. Results: Three dimensional images at longer TE show exchange signal surrounding the choroid plexus, but also more modest exchange near the cerebellar vermis and the cerebellar and cerebral cortices. Impact: A new strategy for T2 selective water exchange imaging can enable in vivo studies of CSF exchange that may reflect changes in glymphatic clearance or CSF production with aging, Alzheimer’s disease, intracranial hypertension and other disorders.