The Angles between A1 and A2 Segments of the Anterior Cerebral Artery Measured by Three-dimensional Computer Tomographic Angiography and The Relationship with Anterior Communication Artery Aneurysms

Purpose:To evaluate the angles between A1 and A2 segments of the anterior cerebral artery and the relationship with anterior communication artery aneurysms.Methods:Thirty-two cases of anterior communicating artery aneurysm and 35 cases of non-anterior communicating artery aneurysm which were randomly chosen in the same period were analyzed in our study,and A1-A2 segment angles(lateral angles) were mearsured on 3D-CTA.Results: In the 32 cases of anterior communicating artery aneurysm,19 cases of A1 segment of anterior communicating artery were dominant type,13 cases was a balanced type.The average A1-A2 segment angle of anterior communicating artery aneurysm group were 99.0°±18.8° measured by 3D-CTA,rather than the average angle of the non-anterior communicating artery aneurysm group(118.1°±16.4°),there was statistically difference between the two group(P0.001).In the case of A1 balanced type,the average A1-A2 angle of the side associated with ACoA aneurysm was 96.3°± 18.8°,which was smaller than the non-aneurysm side(115.2°±15.3°)(P0.05).Conclusion:The smaller the angle between A1-A2 junction is more susceptible to anterior communicating artery aneurysm.This may be related to the hemodynamics change caused by the inappropriate angle.