Assessing Glymphatic Dynamics in the Human Brain Using Cardiac-Gated diffusion MRI at Ultra-High Field

Motivation: The glymphatic system is a perivascular network of thin vessels, vital for brain waste clearance, influencing neurological health. Goal(s): This study investigates the effects of the cardiac cycle, echo times, and b-values on glymphatic flow quantification using diffusion MRI at ultra-high field. Approach: We measured diffusion along (D||) and perpendicular (D⊥) to the perivascular spaces during systole and diastole at different echo times, and b-values to assess glymphatic dynamics. Results: Our findings show that D* is higher during systole, especially at lower b-values, indicating that the IVIM regime with cardiac gating is better suited for quantifying glymphatic flow. Impact: This study shows how glymphatic flow quantification using diffusion MRI in the human brain is influenced by the cardiac cycle, echo time and b-value, paving the way for the non-invasive assessment of glymphatic flow in clinical practice.