The Study of Anatomical Variations of the Circle of Willis in Patients Who Underwent Magnetic Resonance Angiography (MRA) of Brain at Phramongkutklao Hospital

Abstract

Introduction: Circle of Willis (CoW) looked like ring of blood vessel. Communicate between anterior lobe and posterior lobe of brain for increase blood to brain if there have blood vessel stenosis. Objective: Study the anatomical variations of the circle of Willis (CoW) in Thai population and search for relationship between type of variation and ischemic stroke. Materials and Methods: In 330 patients during May 2014 to February 2015 who underwent Magnetic Resonance Angiography of the brain at Phramongkutklao Hospital by MRI 1.5 Tesla, Achieva TX Philips were studied. Results: The prevalence of CoW variations is 72.7%, anterior part of CoW variation is 38.5% and posterior part of CoW was 64.8%. The most common type of anterior CoW variation is Hypoplasia or absence of ACoA (13.9%), followed by Two (or more) ACoAs (7.9%), One precommunicating segment of an ACA is hypoplastic or absent, the other precommunicating segment gives rise to both postcommunicating segments of ACA (5.5%) respectively. The most common type of posterior CoW variation is Unilateral PCoA (17%), followed by Hypoplasia or absence of both PCoA and isolation of the anterior and posterior parts of the circle at this level (15.2%), PCA originates predominantly from the ICA: unilateral fetal type PCA (13%) respectively. There were association between the CoW variations and ischemic stroke. Unilateral PCoA, Hypoplasia or absence of both PCoA and isolation of the anterior and posterior parts of the circle at this level were the risk factor of ischemic stroke. Conclusion: The prevalence of CoW variations in Thai population is 72.7%. Unilateral PCoA and Hypoplasia or absence of both PCoA and isolation of the anterior and posterior parts of the circle at this level are the risk factor of ischemic stroke.