Supplementary Material for: Aging-related morphological remodeling in cerebral arteries: A quantitative magnetic resonance angiography study

Introduction: Age-related arterial remodeling is a key contributor to cardiovascular disease, but morphological changes in cerebral arteries with aging remain poorly characterized. We aimed to investigate age-related alterations in cerebral arterial morphology using quantitative analysis. Methods: This retrospective observational study analyzed brain magnetic resonance angiography images from 1,168 healthy individuals without cerebrovascular disease. An automated arterial measurement system was used to quantify morphological features, categorized into size metrics (e.g., area), shape metrics (e.g., minimum [min]-maximum [max] diameter ratio), and tortuosity metrics (e.g., curvature). Correlation analyses were performed between age and arterial features, and multivariable regression analyses were conducted to evaluate age-related effects across the entire cerebrovascular tree and individual cerebral arterial segments. Results: Luminal area increased steadily with age (rho = 0.217, p < 0.001). The min-max diameter ratio remained stable until the fifties and then increased rapidly after the fifth decade (rho = 0.144, p < 0.001), reflecting more circular vessel configurations. Curvature did not change significantly with age. Age was independently associated with the global features of cerebral arteries, including mean area (β = 0.285; 95% CI, 0.222–0.347) and mean min-max diameter ratio (β = 0.215; 95% CI, 0.147–0.282), but showed no significant association. At the level of individual artery analysis, the effect of age on luminal area was more pronounced in larger arteries, whereas age-related changes in the min–max diameter ratio were more evident in medium-sized arteries. Interaction analysis between age and vascular risk factors revealed a significant effect of interaction on arterial shape. Conclusions: Cerebral arteries show distinct age-related morphological alterations, characterized by luminal enlargement and greater circularity. These changes vary with arterial size and location, suggesting differential susceptibility of cerebral arteries to the effects of aging.