The goal of this study was to explore the associations of intracranial vascular features measured from non-contrast enhanced magnetic resonance angiography (NCE-MRA), including total artery length, number of branches, and tortuosity with global cognitive function that was measured with the Montreal Cognitive Assessment (MoCA) score.

Identifying novel risk markers is considered a critical component for understanding the vascular contribution to cognitive impairment. Several imaging modalities can be used to measure brain blood flow for patients with cognitive impairment. These include arterial spin labeling (ASL) magnetic resonance imaging (MRI), transcranial doppler, and phase contrast (PC) MRI among others. Previous studies have established a correlation between NCE-MRA intracranial vascular features with ASL or PC flow measurements.

In 29 older subjects with atherosclerotic disease, intracranial artery features were measured on two NCE-MRA sequences (i.e. time of flight, TOF and simultaneous non-contrast angiography and intraplaque hemorrhage, SNAP). Blood flow measurements from ASL CBF, and PC CBF were also recorded. A recently developed sequence named iSNAP was performed to obtain whole-brain MPRAGE-like 3D T1W structural images for image registration. 2D T2W FLAIR images were acquired for detecting cerebral white matter hyperintensities (WMHs).  Linear regression was performed to study the associations of flow measurements with global cognition.

The intracranial artery length and number of branches on NCE-MRA, ASL CBF and PC CBF were found to be positively associated with MoCA score (P < 0.01). The associations remained significant, except for ASL CBF, after adjusting for clinical covariates and WMH volume. The association remained significant for artery length and number of branches on TOF after adjusting for clinical covariates and ASL CBF or PC CBF.

Our findings suggest that these intravascular features could be useful markers of cerebrovascular health in individuals with cognitive impairment.