The feasibility of mean apparent propagator (MAP)-MRI for Assessing the Glymphatic function

Motivation: Glymphatic system involves dynamic regulation of cell morphology and interstitial fluid dynamics in brain parenchyma, but there still lacks MRI methods assessing such processes. Goal(s): To explore the feasibility of mean apparent propagator (MAP)-MRI to measure glymphatic function in brain parenchyma. Approach: We altered the glymphatic function using different anesthesia protocols (ketamine/xylazine (K/X) and isoflurane (ISO)) and measured MAP-MRI in rat brain in vivo. Results: MAP-MRI effectively captured differences in the extracellular space in various brain regions (e.g. PAG) of rats under K/X and isoflurane anesthesia. The observed changes were as predicted: K/X anesthesia promoted water displacement more effectively than isoflurane. Impact: Given the significant role of the glymphatic system in maintaining brain homeostasis, our findings suggest MAP-MRI's sensitivity to glymphatic function, which makes it a potentially viable method for monitoring glymphatic activity.