Increased intracerebral blood pulsatility as measured with 7T MRI is related to cognitive impairment in a memory clinic sample

Motivation: Alzheimer's disease and aging affect cerebral hemodynamics. Ultra-high field MRI (7T) enables measurement of blood flow velocity in small arteries (lenticulostriate arteries; LSAs) and pulsatility damping from larger vessels (middle cerebral artery; MCA). Goal(s): To explore the relationship between small vessel pulsatility, damping, and cognitive performance in cognitively healthy elderly (n=34) and memory clinic patients (n=17). Approach: Leveraging 7T phase-contrast MRI, the MCA's and LSA's pulsatility indices and respective damping factor (DF) were calculated, and their Spearman's correlations with cognitive performance were analysed. Results: Reduced DF correlates with lower global cognition, executive functioning and memory in memory clinic patients, but not in controls. Impact: This study highlights the clinical value of 7T MRI in measuring small vessel pulsatility and damping, revealing insights into local fluid dynamics and the distinct mechanisms related to cognitive performance in memory clinic patients and healthy controls.