Noninvasive magnetic resonance imaging measures of glymphatic system activity

Abstract

The glymphatic system is described as a perivascular brain network that facilitates CSF and interstitial fluid exchange. It has been reported that the activity of the glymphatic system changes dynamically with sleep, aging, alcohol intake, etc., and it is described that it is closely related to the onset of dementia. It has also been suggested that a contribution of an impaired glymphatic system to the accumulation of amyloid–beta (Aβ), which are identified as pathological hallmarks of Alzheimer disease (AD). MRI measurements, such as the diffusivity along the perivascular space (PVS) represented by the ALPS index, the PVS volume, and the fractional volume of free water (FW) in the brain parenchyma, were recently revealed as promising candidates for the evaluation of the glymphatic system function.