Coupling between CSF inflow and ventricle volume change

Motivation: CSF plays a crucial role in clearing metabolic waste from the brain and it exhibits low-frequency oscillations during sleep. Goal(s): To identify whether lateral ventricle volume (LVV) exhibits dynamic changes that relate to CSF flow. Approach: Using accelerated EPI to measure CSF dynamics, we simultaneously quantified the size of the lateral ventricle for each image frame using the tool "SynthSeg". Results: We observed that lateral ventricle volume varies by as much as 6-8% over time. Notably, changes in MRI signals induced by CSF inflow are coupled with lateral ventricle volume fluctuations in the low-frequency range (<0.3 Hz) during both awake and sleep states. Impact: This discovery not only provides an alternative method for characterizing CSF dynamics but also offers new insights into the origin of the global BOLD signal change and the complex and dynamic properties of components of the glymphatic system.