The Relationship Between Anatomic Variation Of The Willis Circle And Cerebrovascular Disease: An Investigation On 64-detecter CT Angiography

Part one: The relationship between cerebral aneurysms formation in communicating arteries and anatomic variation of the Willis circleObjective To study the relation of aneurysm formation on communicating branches with dysplasia of horizontal segment of anterior cerebral artery and fetal type posterior cerebral artery; To study the relation between aneurysm formation in anterior communicating artery and the angel of A1 and A2 segments of anterior cerebral artery Materials and Methods Fifty-six patients harboring communicating aneurysms demonstrated by 64-slice CTA were invovled in this study,among which 26 cases with anterior communicating aneurysms, 30 cases with posterior communicating aneurysms.Fifty healthy matched volunteers were used as controls; A1-A2 angle of anterior cerebral artery were measured by three-dimensional computed tomographic angiography on 25 patients harboring anterior communicating aneurysms and 20 healthy volunteers.All date were analyzed by SPSS 11.0 statistical software package. Qualitative data express as frequency(rate), Chi-square criterion were performed among groups; Quantitative data express as mean±standard deviation , Independent-Sampler T test were performed among groups. Difference with P<0.05 was considered as significant. Results. In patients with anterior communicating aneurysms ,65.4%(17/26) had dysplasia (hypoplastic or absent) of the A1 segment, which is higher than those in patients with posterior communicating aneurysms (PCA) and control with great significance. In patients with posterior communicating aneurysms,31.7% (19/60) had fetal type of posterior cerebral artery (FTP ) in PCA, which is higher than those in patients with anterior communicating aneurysms and normal control.The average A1-A2 angle was determined to be 106.27±19.57 degrees(mean±standard deviation) in 25 patients with anterior communicating aneurysms,which is lower than that(127.42±15.20degrees) in 20 volunteerss without aneurysms (P<0.01). The A1-A2 angle in aneurysm side was 95.96±16.38 degree,which is lower than that (133±23.11 degree)in non-aneurysm side (P<0.01) in 8 patients with aneurysms without morplastic A1 segments.Conclusions The development of cerebral aneurysms in communicating branches maybe closely related with dysplasia of horizontal segment of anterior cerebral artery and fetal type of posterior cerebral artery;The angle between A1 and A2 segment maybe have important role in the formation of ACoA .Part two: An investigation on the relationship between end-results of internal carotid artery stenosis or occlusion and anatomic variation of the Willis circleObjective To study the relationship between end-results of internal carotid artery stenosis or occlusion and anatomic variation of the Willis circle Materials and Methods Twenty patients with internal carotid artery stenosis or occlusion demonstrated by 64-slice CT Angiography (CTA ) were involved in this study. Both unilateral and bilateral lesions are ten cases, They were divided into 2 groups :large area of cerebral infarction group(n=8) and no-cerebral infarction group(n=12) according to the imaging manifestation.All date were analyzed by SPSS 11.0 statistical software package. Data express as frequency(rate),Chi-square criterion were performed among groups Difference with P<0.05 was considered as significant.Results. In infarction group,only 37.5%(3/8) demonstrated a complete anterior circulation of the circle and 12.5%(1/8) demonstrated a complete posterior circulation of the circle, which is obvious lower than those in no-infarction group that is 100%(12/12) and 75%(9/12).Conclusions End-results of internal carotid artery ( ICA) stenosis or occlusion maybe closely related with anatomic variation of the CW.