Anatomical variations of the circle of Willis: evaluation with CT angiography

Abstract

Objectives: The aim of this study was to investigate anatomic variants and anomalies of the circle of Willis using computedtomography angiography (CTA).Methods: CTA images of 770 patients obtained from Tepecik Training and Research Hospital between January 2012 to January2017 were retrospectively reviewed to identify the anatomical vascular variations of the circle of Willis.Results: After exclusion, 751 patients (348 females, 403 males, mean age 54.6 years, range 18–90 years) were enrolled into thestudy. The anatomical variations related to the posterior communicating artery (PcoA) were the most common, whereas anatomicalvariations related to the middle cerebral artery (MCA) were the least common variations among arteries. Hypoplasia of theA1 segment was the most common (14.6%) variation of the anterior cerebral artery (ACA) and fenestration of this artery wasthe least common variation (1,06%) observed only in A1 segment. Bilateral absence of the PcoA was seen in 27.56% of thepatients. Fenestration was more commonly detected in anterior communicating artery (AcoA) (10.12%), followed by MCA(1.06%), ACA (1,06%) and PCA (0.67%). Duplication was the least common variation which was detected in MCA, AcoA andPcoA.Conclusion: Arterial variations of the circle of Willis are not rare and can be non-invasively evaluated using CTA.