Anatomical Variation of the Circle of Willis in Males and Females on 3D MR Angiograms

Higher prevalence of circle of Willis anomalies were detected in brains with signs of ischemic infarction, so the aim of this work is to study the anatomical variation of the circle of Willis in a trial to detect sex‐related differences as regard the component vessels and their average diameters. Sixty males and 60 females' healthy control adult subjects were observed. In addition, ten cadavers' brains were obtained from the Anatomy department Faculty of Medicine, ASU for examination of the circle of Willis. The results indicated that, the anterior part of the circle was completed in 70% males and 75% females of the study sample. The most common variant of the anterior part was the single anterior communicating artery followed by the hypoplastic or absent anterior communicating artery. The posterior part of the circle was % males and 58% females. The most common 48completed in anatomical variant was the bilateral posterior communicating arteries, followed by the unilateral posterior communicating artery. An entirely complete circle was found only in 45% of the entire population; and it was higher in females than in males. The vessels diameters were smaller in females than in males except for the posterior communicating artery. The present study shows the amazing great variability of the anatomy of the circle of Willis in the asymptomatic persons. This has to be considered during radiological interpretation and would be reported in the current anatomy text to be aware of all these normal variations.