Assessment of anatomical variants at Circle of Willis using Magnetic Resonance Angiography among patients with suspected vascular pathology of brain in tertiary care hospital, Chennai

Abstract

Introduction: Circle of Willis, is an anatomical structure that provides an anastomotic connection between anterior and posterior circulations in order to provide a collateral flow in case of any brain pathology. Vascular
variations have been investigated with autopsy, Computed tomography
Infarct, Collaterals angiography (CTA) and Magnetic Resonance Angiography (MRA) among other techniques to study blood artery morphology. By eliminating the requirement for iodinated contrast material and in certain cases, ionising radiation entirely, MRA has become a viable alternative to traditional angiography and CT angiography. 

Aim and Objectives: To assess the anatomical variants at CoW using MRA among subjects with suspected vascular pathologies and additionally determine the average vessel diameter and evaluate gender related differences.
Materials and Methods: A cross sectional study was conducted in the Department of Radiology, at a tertiary care hospital, for a period of 2 years. A total of 120 cases with suspected vascular pathologies of brain (Infarct/ Haemorrhage/ Mass lesion/ signs of ischemia/ Atherosclerosis), referred to radiodiagnosis department for MRA were included in this study. All MRA brain scans were done on 3.0 Tesla G.E MRI scanner. 

Results: In this study, 29.2% of participants belonged to age group of 41 – 60 years, followed by 26.7% in 61 -80 years. 56.7 % of participants were males while 43.3% of participants were females. Circle of Willis configuration was complete among 33.3% of cases, partial in 53.3% and incomplete among 13.3%. Most common type of anterior part of CoW.

was A type among 52.5% of cases followed by H type among 12.5% of cases. B type and D type was seen among 10.8% and 10% of subjects respectively. The most common type of posterior part of COW was K type followed by O among 32.5% and 31.7% of cases respectively. N type was noted among 15.8 % of cases. Other types of posterior part of COW were least found in this present study.
Conclusion: Variations in CoW are common in both anterior and posterior circles and the vessel diameter in few selected vessels differ with age, gender and type of completeness of CoW. Hence, large scale studies are warranted in order to figure out the proportion of subjects with varying morphological CoW.