Willis环三维时间飞跃法磁共振成像的形态、解剖变异及脑底动脉直径测量

通过三维时间飞跃法磁共振成像建立正常国人Willis环的形态、解剖变异及各组成血管直径的正常参考值,探讨其临床意义,决定在Willis环的解剖中是否存在年龄或性别差异。153例健康志愿者和体检者做头MRA检查,显示Willis环,根据其完整情况分为I型(Willis环完整)、II型(Willis环前循环完整后循环不完整)、III型(Willis环前循环不完整后循环完整)、IV型(Willis环前后循环均不完整),根据各血管发育情况,各型又分为典型型、变异型、发育不良型和混合型4种亚型,并对各组成血管直径进行测量。结果表明:153例中,I型占34.64%,II型占47.71%,III型占5.23%,IV型占12.42%。各型及各亚型的年龄、性别差异无显著性。前交通动脉显示率为87.58%,后交通动脉显示率为65.34%,胚胎型大脑后动脉出现率为20.92%。MRA评价Willis环的形态和变异有重要的临床意义,脑底动脉MRA正常值可作为临床判断脑血管疾病的参考。

Investigation of Morphology and Anatomic Variations of Circle of Willis and Measurement of Diameter of Cerebral Arteries by 3D-TOF Angiography

To observe the morphology and anatomic variations of the circle of Willis and its clinical significance. To measure and establish the normal reference parameters of average diameters of its component vessels in the healthy Chinese by using 3D-TOF MR angiograms and to determine whether age-or sex-related differences exists in the circle' anatomy. MRA was performed in 153 healthy subjects. According to its integrity, Willis'circle was divided into four types: (1) Type I, showing an intact circle. (2) Type II, having a complete anterior circulation but an incomplete posterior circulation. (3) Type III, having an incomplete anterior circulation but a complete posterior circulation. (4) Type IV, having an incomplete anterior and posterior circulation. Based on the development of the components of the circle, each type was subdivided into four subtypes: typical, variable, hypoplastic and mixed. The statistically significant differences were not found in each type or subtypes between the different age and sex groups. Result of 153 cases, Type I, II, III and IV was found in 53 (34.64%), 73 (47.71%), 8 (5.23%), and 19 (12.42%) respectively. The display rate of the anterior and the posterior communicating arteries was 87.58%o (134/153) and 65.34% (100/153) respectively. Display rate of fetaltype posterior cerebral artery(PCA) was 20.92%. 3D-TOF MR angiography has important clinical significance for evaluating morphology and anatomic variations of circle of Willis. The normal values of diameter of cerebral arteries on MR angiograms may play a reference role in diagnosing cerebral vascular diseases.