Associations of intracranial artery length and branch number on non-contrast enhanced MRA with cognitive impairment in individuals with carotid atherosclerosis

Abstract

Developing novel risk markers for vascular contributions to cognitive impairment and dementia is important. This study aimed to extract total length, branch number and average tortuosity of intracranial distal arteries (A2, M2, P2 and more distal) from non-contrast enhanced magnetic resonance angiography (NCE-MRA) images, and explore their associations with global cognition. In 29 subjects (aged 40–90 years) with carotid atherosclerotic disease, the 3 intracranial vascular features on two NCE-MRA techniques (i.e. time of flight, TOF and simultaneous non-contrast angiography and intraplaque hemorrhage, SNAP) were extracted using a custom-developed software named iCafe. Arterial spin labeling (ASL) and phase contrast (PC) cerebral blood flow (CBF) were measured as references. Linear regression was performed to study their associations with global cognition, measured with the Montreal Cognitive Assessment (MoCA). Intracranial artery length and number of branches on NCE-MRA, ASL CBF and PC CBF were found to be positively associated with MoCA scores (P < 0.01). The associations remained significant for artery length and number of branches on NCE-MRA after adjusting for clinical covariates and white matter hyperintensity volume. Further adjustment of confounding factors of ASL CBF or PC CBF did not abolish the significant association for artery length and number of branches on TOF. Our findings suggest that intracranial vascular features, including artery length and number of branches, on NCE-MRA may be useful markers of cerebrovascular health and provide added information over conventional brain blood flow measurements in individuals with cognitive impairment.

Association between morphologic features of intracranial distal arteries and brain atrophy indexes in cerebral small vessel disease: a voxel-based morphometry study

“…In another study, it was discovered that the length of intracranial arteries and the number of branches observed on TOF MRA were linked to Montreal Cognitive Assessment (MoCA) scores. These findings were not influenced by carotid stenosis, age, systolic blood pressure, use of anti-hypertensive drugs, or cerebral blood flow (CBF), indicating that they could offer supplementary insights into cerebrovascular health beyond conventional blood flow measurements (21). As commonly acknowledged, advanced age and hypertension are the primary risk factors for CSVD.…”

“…The intracranial artery features observed on MRA should not be considered as an accurate representation of the true vascular morphology within the brain. Rather, they serve as proxies for various factors that affect the visibility and luminal signal of distal arteries (such as A2, M2, P2 and more distal) on MRA scans (21). These factors include, but are not limited to, brain blood flow, as well as wall thickening-induced luminal narrowing (20,49,50).…”

“…Furthermore, Gould et al (20) discovered that the vascular features of distal arteries on 3D-TOF MRA, such as vessel length and the number of branches, may serve as surrogate markers of blood flow. Moreover, these vascular features may also be affected by other factors, such as wall thickening-induced luminal narrowing in the distal arteries (21). Therefore, these vascular features may provide distinctive information regarding blood flow and luminal narrowing in distal arteries.…”