Basilar Artery Diameter Is Inversely Associated with Fetal Type Circle of Willis.

Background: The relationship between basilar artery (BA) diameter and Circle of Willis (CoW) configuration has been scarcely investigated. We aimed to assess this association in community-dwelling older adults.

Methods: MRAs of 346 individuals were reviewed. Using generalized linear models adjusted for demographics and cardiovascular risk factors, we assessed the relationship between BA diameter and fetal and non-fetal types CoW, as well as the impact of this relationship on BA ectasia prevalence.

Results: In the total population, the mean BA diameter was 3.13 ± 0.68 mm and 7 subjects (2%) had ectasia (BA diameter >4.5 mm). In 248 subjects with non-fetal types CoW, the mean BA diameter was 3.32 ± 0.62 mm, and 2.8% had ectasia. In 98 subjects with fetal type CoW, the mean BA diameter was 2.66 ± 0.58 mm, and no individual had ectasia. The BA diameter was smaller in subjects with fetal type CoW than in those with non-fetal types (β 0.65; 95% CI 0.51-0.79; p < 0.001). Individuals with fetal type CoW have an 18% reduction in BA diameter compared to those with non-fetal types, independently of demographics and cardiovascular risk factors.

Conclusion: This study shows an inverse relationship between the BA diameter and the presence of fetal type CoW.