Fig. 1. The image of an aneurysm is classified as a classical neck type (Type C). The larger DA is defined as DA A, and the other DA is defined as DA B. LA mean diameter of the vessel measure at the LA1 and LA₂, and the other vessel is measured as LB; the DA ratio is defined as LA/LB. The angle between the parent artery and DA A is defined as angle A, and the angle between the parent artery and DA B is defined as angle B; the LA ratio is defined as angle A/angle B. DA, daughter artery; LA ratio, lateral angle ratio; LA, diameter of DA A; LB, diameter of DA B.