MRA Classification of the Artery Structures at the Base of the Brain / 中国医科大学学报

ABSTRACT

Objective To observe and classify the structure of the circle of Willis by using magnetic resonance angiographic(MRA)method. Methods A total of 2104 MRA head images from October 2013 to May 2015 in Shenyang Weikang Hospital was retrospective analyzed ,and the structure was classified by anterior circle or posterior circle according to the actual situation of the cerebral basilar artery. Results According to the origin of anterior cerebral artery and whether there was anterior communicating artery or not ,anterior circle was classified into three types:type Ⅰ,type Ⅱ and type Ⅲ. Type Ⅱ was classified into two subtypes,namely,type ⅡR and type ⅡL. Posterior circle,on the basis of whether there was posterior communicating artery or not,was classified into three types,which were type Ⅰ,type Ⅱ and type Ⅲ. According to the origin of posterior cerebral artery,type Ⅰ was classified into four subtypes,including type ⅠB,type ⅠC,type ⅠRC and type ⅠLC;type Ⅱ was classified into eight subtypes,including type ⅡBR,type ⅡBL,type ⅡCR,type ⅡCL,type ⅡRCR,type ⅡRCL,type ⅡLCR and type ⅡLCL;type Ⅲ was classified into four subtypes,including type ⅢB,type ⅢC,type ⅢRC,type ⅢLC. Conclusion There is a correlation among the different types of cerebral basi-lar artery,and each type of artery has their own sources of blood supply and the traits of communication compensation. When the anterior circle and posterior circle were both type Ⅲ,the complete ring structure of cerebral basilar artery,namely the circle of Willis,was formed. The existing rate of the circle of Willis was about 10.7%. Understanding of the differences among the individual types of arteries has great significance to the prevention and treatment of the cerebrovascular disease.