Machasio Roy Munialo, Nyabanda Rose, Mutala Timothy Musila
University of Nairobi, Department of Diagnostic Imaging and Radiation Medicine, Kenya.
Kenyatta National Hospital, Kenya.
Radiol Res Pract. 2019 Jun 16;2019:6380801. doi: 10.1155/2019/6380801. eCollection 2019.
There is a wide variation in the anatomy of the CW in different individuals and population groups. The purpose of this study was to determine the proportion of variant anatomy of the circle of Willis (CW) and associated anomalies in patients with suspected cerebrovascular disease referred for cerebral computed tomography angiography (CTA) in two tertiary hospitals in Kenya.
This was a cross-sectional descriptive study conducted on 94 patients referred for cerebral CTA at the Kenyatta and Nairobi hospitals from August 2017 to February 2018. MIP and 3D reformatted images were analyzed by two senior radiologists to determine the final configuration of the CW and presence of vascular pathology. Vessels with diameters <0.8 mm were considered to be absent or hypoplastic. Chen et al. classification was used to determine the final configuration of CW.
Complete CW was seen in 37.2% (37.7% vs. 36.6% in males and females, respectively, p=0.909). Type A variant was the commonest anterior variant at 78.7%. Type E variant was the dominant posterior variant at 41.5%. Fetal PCA was demonstrated in 25.5%, unilateral > bilateral fetal PCA. Aneurysms were seen in 24.5% of patients. ACoA aneurysms were commonest at 43.6%. AVMs were seen in 8.5% of patients. Azygous ACA, fenestration, and duplication of vessels and persistent TA were not demonstrated. There is no significant association between aneurysms/AVMs and CW configuration.
The findings in this study demonstrate slight differences in the CW configuration. A higher proportion of complete anterior CW was seen in female patients. Type A anterior and type E posterior circulation variants were the commonest in both males and females. No significant association was demonstrated between CW configuration and occurrence of aneurysms/AVMs in this study. Various methods of classification of CW configuration have been proposed with no standardized method to date, thus the need for consensus building between neuroanatomists, neurologists, neurosurgeons, and neuroradiologists for ease of comparison between similar future studies on the CW.
不同个体和人群组中大脑 Willis 环（CW）的解剖结构存在很大差异。本研究的目的是确定在肯尼亚两家三级医院因疑似脑血管疾病接受脑部计算机断层血管造影（CTA）检查的患者中，Willis 环（CW）变异解剖结构及相关异常的比例。
这是一项横断面描述性研究，对 2017 年 8 月至 2018 年 2 月在肯雅塔医院和内罗毕医院接受脑部 CTA 检查的 94 例患者进行研究。由两名资深放射科医生分析最大密度投影（MIP）和三维重建图像，以确定 CW 的最终构型及血管病变情况。直径<0.8 毫米的血管被视为缺如或发育不全。采用 Chen 等人的分类方法确定 CW 的最终构型。
37.2%的患者可见完整的 CW（男性和女性分别为 37.7%和 36.6%，p = 0.909）。A型变异是最常见的前部变异，占 78.7%。E 型变异是主要的后部变异，占 41.5%。2-5%的患者显示胎儿型大脑后动脉（PCA），单侧>双侧胎儿型 PCA。24.5%的患者可见动脉瘤。前交通动脉瘤（ACoA）最常见，占比 43.6%。8.5%的患者可见动静脉畸形（AVM）。未发现奇静脉型大脑前动脉、血管开窗、血管重复及永存三叉动脉。动脉瘤/AVM 与 CW 构型之间无显著关联。
本研究结果表明 CW 构型存在细微差异。女性患者中完整前部 CW 的比例较高。A型前部和 E 型后部循环变异在男性和女性中均最为常见。本研究未发现 CW 构型与动脉瘤/AVM 的发生之间存在显著关联。目前已提出多种 CW 构型分类方法，但尚无标准化方法，因此神经解剖学家、神经科医生、神经外科医生和神经放射科医生之间需要达成共识以便于未来关于 CW 的类似研究之间进行比较。
