Brain pulsation demonstrated by CSF flow artifacts on FLAIR images might be associated with brain function.

The glymphatic system works to excrete waste products from the brain. If it breaks down, cognitive impairment can occur. The system is mainly driven by arterial and brain pulsation. Brain pulsation is recognized as cerebrospinal fluid (CSF) flow artifacts on fluid-attenuated inversion recovery (FLAIR) imaging. We investigated the factors associated with human brain pulsation. CSF flow artifact grade (score) was defined by comparing the highest intensity in a given region of interest (ROI) to those in reference ROIs of normal white matter in the centrum semiovale on FLAIR imaging. CSF flow scores for eight sites (lateral, third and fourth ventricles, aqueduct, and prepontine cisterns) were measured and summed for a total score (range, 0-16). The prevalence of each finding, specifically risk factors and neuroradiological findings, was compared using multivariate logistic regression models. We evaluated the findings in 1,000 adults (62.8 ± 9.5 years, 569 females) with no history of neurological disorders. Mean CSF flow score was 12.8 ± 1.6. Stepwise and multivariate analyses demonstrated that the score ≤11 as a dependent factor was positively associated with 100-7 test result ≤3, and frontal polar-cranium distance ≥2 mm, and negatively associated with female gender. In addition to frontal atrophy and female gender, the reduction of brain pulsation was associated with brain function during simple calculations as frontal lobe function. Brain pulsation might drive the glymphatic system, and reduction of the pulsation might disturb brain function.