Ravikanth Reddy, Philip Babu
Department of Radiology, St. John's Medical College, Bengaluru, Karnataka, India.
Tzu Chi Med J. 2019 Jan-Mar;31(1):52-59. doi: 10.4103/tcmj.tcmj_167_17.
The purpose of this study is to evaluate and describe the prevalence and patterns of arterial variants in the circle of Willis (CW) seen in noncontrast three-dimensional time-of-flight magnetic resonance angiography in a series of patients with cerebral vascular accidents (CVAs).
A descriptive study was undertaken in 200 patients who presented for screening for CVA in the Department of Radiodiagnosis and Imaging, St. John's Medical College Hospital, Bengaluru, from September 2014 to September 2016.
The most common types of CW in a single subject were anterior variant Type A and posterior variant Type E. Type A in the anterior circulation is the normal adult pattern. There is a single anterior communicating artery. The internal carotid artery bifurcates into the precommunicating segment of the anterior cerebral artery and middle cerebral artery. Type E in the posterior circulation is hypoplasia or absence of both posterior communicating arteries and isolation of the anterior and posterior parts of the circle at this level. Overall, CW variants were slightly more common in women than in men.
Our findings show that the configuration of the CW may vary greatly in the general population. The wide range in the morphology of CW warrants further research on various races and larger populations to confirm the influence of genetic, regional, environmental, and hemodynamic factors or their combination.
本研究旨在评估并描述一系列脑血管意外（CVA）患者在非增强三维时间飞跃磁共振血管造影中所观察到的 Willis 环（CW）动脉变异的发生率及模式。
对 2014 年 9 月至 2016 年 9 月期间在班加罗尔圣约翰医学院医院放射诊断与影像科进行 CVA 筛查的 200 例患者进行了一项描述性研究。
单个受试者中最常见的 CW 类型是前循环 A 型变异和后循环 E 型变异。前循环中的 A 型是正常成人模式。有一条前交通动脉。颈内动脉分为大脑前动脉和大脑中动脉的交通前段。后循环中的 E 型是双侧后交通动脉发育不全或缺失，且在此水平上 Willis 环的前后部分相互分离。总体而言，CW 变异在女性中比在男性中略为常见。
我们的研究结果表明，在一般人群中，Willis 环的结构可能有很大差异。Willis 环形态的广泛差异值得对不同种族和更大规模人群进行进一步研究，以证实遗传、区域、环境和血流动力学因素或其组合的影响。
