Tortuous extracranial arteries contribute to white Matter hyperintensities in aging brains

White matter hyperintensity (WMH) is a hallmark imaging biomarker of cerebral small vessel disease and are strongly associated with vascular cognitive impairment in the elderly. Morphological changes in large extracranial brain-feeding arteries, such as the internal carotid (ICA) and vertebral arteries (VA), may alter intracranial hemodynamics and contribute to WMH development. This study examined the relationship between arterial tortuosity and WMHs using magnetic resonance angiography (MRA).

Seventy-eight participants underwent time-of-flight (TOF) MRA and phase-contrast (PC) MRI to assess arterial morphology and blood flow. After excluding three for poor image quality, 75 subjects were analyzed. Arterial tortuosity was quantified using the inflection count metric (ICM) and ICA angle. Global cerebral blood flow (CBF) was estimated with PC-MRI and compared against pseudo-continuous arterial spin labeling (pCASL) to determine whether it could be a reliable surrogate measurement to reflect intracranial blood supply.

Participants with severe WMHs (Fazekas ≥2) demonstrated greater tortuosity (higher ICM and larger ICA angles) and lower blood flow than those with mild WMHs. Females showed more tortuous arteries, greater WMH burden, and higher susceptibility to hypoperfusion. Correlation analyses revealed a positive association between tortuosity and WMH volume.

These findings highlight the role of extracranial arterial tortuosity in WMH burden and reveal sex-specific differences in vascular vulnerability. The results underscore the need for further investigation into how age-related vascular remodeling contributes to WMH development and cognitive decline.