Anatomical variations of the circulus arteriosus cerebri (Circle of Willis): A computed tomography angiography study

This study primarily aims to examine the frequency of anatomical variations in the Circle of Willis (CW) among the Turkish population using computed tomography (CT) angiography. The study included CT angiography images of 298 patients in total, comprising 131 females and 167 males. The configurations of the anterior and posterior parts of the Circle of Willis (CW) were analyzed and categorized. The frequency of each variant, along with the number of complete anterior and posterior circles, was recorded. The most common CW variation was found in the posterior segment. In the posterior segment, posterior communicating arteries (PComA) hypoplasia was the most frequently observed variation in both males (right: 51, left: 54) and females (right: 49, left: 56), followed by bilateral PComA hypoplasia. The adult configuration was seen in 243 individuals (99 females, 144 males). The fetal configuration was identified in 46 individuals (29 females, 17 males), while the transitional configuration was found in 9 individuals (3 females, 6 males). CTA is a safe and simple method to map blood vessels. Knowing Circle of Willis variations can help plan surgeries and reduce stroke risk. Checking CW anatomy routinely may support better treatment decisions.