ABSTRACT
Objective To observe the relationship between the integrity of Willis circle and aneurysm with MSCT angiography.Methods CTA data of 580 patients with intracranial vascular lesions were retrospectively analyzed.The morphological structure of Willis circle and the occurrence of aneurysm were observed based on axial thin-layer,VR,MIP and MPR images.According to the integrity,Willis circle were divided into type Ⅰ (Willis circle complete),type Ⅱ (the anterior circulation complete but the posterior circulation incomplete),type Ⅲ (the anterior circulation incomplete but the posterior circulation complete) and type Ⅳ (both the anterior and posterior circulation incomplete) for statistical analysis.Results For the classification of Willis circle,there were 118 cases of type Ⅰ (118/580,20.34％),344 of type Ⅱ (344/580,59.31％),25 of type Ⅲ (25/580,4.31％) and 93 cases of type Ⅳ (93/580,16.03％).The incidence of Ⅰ-Ⅳtypes of Willis circle with aneurysm accounted for 16.10％ (19/118),14.83％ (51/344),32.00％ (8/25) and 23.66％ (22/93),respectively.The incidences of aneurysm in patients with different types of Willis circlewere statistically significant (x2=8.013,P=0.046).There was statistical difference of the type of Willis circle between different genders (x2=12.631,P=0.006),and the incidence of aneurysm in females was higher than that in males (25.00％ [63/252] vs 11.28％ [37/328];x2 =18.80,P＜0.025).Conclusion Most Willis circle were not complete,and incomplete Willis circle aneurysm tended to occur in females with higher aneurysm rate.