Variations of the circle of willis determined via magnetic resonance angiography: A single-center analysis of the serbian population

Introduction: The circle of Willis (CoW) represents the collateral pathway between large brain-feeding arteries, the knowledge of which is important in interventional and neurosurgical procedures, in the diagnosis and planning of procedures in acute stroke and subarachnoid hemorrhage. Aim: The study aims to determine the prevalence of variations of the CoW in patients from Serbia via magnetic resonance angiography (MRA). Material and Methods: The study was conducted as a retrospective study at the Center for Imaging Diagnostics, Oncology Institute of Vojvodina. Magnetic resonance imaging was analyzed in 665 patients of both sexes (471 females and 194 males), who underwent MRA during 2018 and 2019. Results: Complete CoW was found in 48.42% of cases, mostly in females (68.01%). Partially complete CoW and incomplete CoW were encountered in 38.05% and 13.55% of patients, mostly in females (73.52% and 73.33%). Anterior circulation variations were seen in 27.41% of cases, higher in females (63.83%), most commonly A1 anterior cerebral artery hypoplasia (9.32%). Posterior circulation variations were seen in 46.36% of cases, higher in females (79.25%), most commonly posterior communicating (PCom) artery hypoplasia (25.56%). Combined variations were seen in 26.24% of patients, with higher prevalence in females (73.33%). The prevalence of variations of posterior circulation between male and female patients was statistically significant (P = 0.007) and was higher in females. Discussion and Conclusion: This study showed that the most common variations were that of the posterior circulation, most commonly PCom artery hypoplasia. Complete CoW was found in <50% of cases (48.42%).