Assessing pulsatile waveforms of paravascular cerebrospinal fluid dynamics within the glymphatic pathways using...

Area of Science:

• Neuroscience
• Medical Imaging
• Fluid Dynamics

Background:

• Cerebrospinal fluid (CSF) in surface perivascular spaces (sPVS) is crucial for brain waste clearance.
• Arterial pulsations are hypothesized drivers of paravascular flow, but dynamics remain poorly understood.
• A clinically practical method for measuring human brain sPVS dynamics is lacking.

Purpose of the Study:

• To introduce and validate a non-invasive imaging and quantification framework for assessing pulsatile CSF dynamics in human sPVS.
• To investigate the relationship between CSF flow, arterial pulsations, and aging.

Main Methods:

• Dynamic Diffusion-Weighted Imaging (dDWI) with low b-values (150s/mm²) and retrospective cardiac gating.
• Synchronized measurements with heartbeat to reveal CSF flow waveforms over a cardiac cycle.
• Data-driven approach for automatic sPVS identification and whole-brain fluid waveform quantification.

Main Results:

• dDWI successfully visualized cardiac-cycle-dependent CSF flow waveforms in sPVS.
• CSF waveform shape correlated with arterial wall pressure waveforms, supporting vascular pumping.
• Aging was associated with wider systolic peaks in CSF waveforms, suggesting altered vascular compliance.

Conclusions:

• dDWI is a feasible, reproducible, and sensitive method for assessing human brain sPVS fluid dynamics.
• Preliminary data indicate age-related alterations in paravascular pumping mechanisms.
• The rapid dDWI technique holds potential for studying fluid dynamics in health and disease.