Evaluation of Anatomical Variations of the Circle of Willis: Computed Tomography Angiography Study

Abstract
Background: Circle of Willis (COW) main function is the brain protection from ischemia, as it ensures a constant and regular blood flow to the brain. The anatomy of Circle of Willis (COW) showed a wide variations in different individuals as regard age and sex.
Aim of Study: The current study was designed to elucidate the prevelance of COW variations in its anterior and posterior parts regarding age and sex, as well as the differences in the mean diameter of vessels forming the circle using Computed Tomography Angiography (CTA).
Material and Methods: The study was conducted on one hundred patients using cerebral CTA, Maximum Intensity Projections (MIP) and 3D reformatted images were assesed to determine the COW configuration and exclude the presence of any pathology. Frequency of variations in its two parts as regard age and sex. The diameters of arteries were measured and the mean difference were calculated.
Results: The study was designed on 100 patients (52% male and 48% female) in two different age young group _40. The mean diameters of arteries were higher in younger age group 56% compared to 44% in old age. Complete circle was encountered in 70% of cases, while 30% were incomplete. The variations recorded were 55% of cases in anterior part of the circle (Ant V) and 45% of cases in its posterior part (Post V) that showed statistically sig difference in anterior part than posterior part in the mean arteries diameters.
Conclusion: The circle of Willis showed different ana-tomical variations. Knowledge of the frequency of these variations is very important especially for surgery in cerebrov-ascular disease and in interventional procedures as a guide for entry in these procedures.