Significance of Aspect Ratio as Predictor of Intracranial Aneurysm Rupture

Koo, Sun Ho; Kim, Bum Tae; Park, Hyung Ki; Cho, Sung Jin; Chang, Jae Chil; Choi, Sun Kwan; Byun, Bark Jang

Abstract

OBJECTIVE
The size of intracranial aneurysm has been well known as a risk factor of aneurysmal rupture. The aneurysmal shape affects risk of rupture differently even though the size is similar. Aspect ratio corresponds well with morphologic variability. In this study we investigated the significance of aspect ratio as a predictor of intracranial aneurysm rupture.
METHODS
The authors reviewed the retrospectively the medical records of consecutive patients with ruptured and unruptured intracranial aneurysms who underwent cerebral angiography from January 2001 to December 2005. A total of 156 patients underwent cerebral angiography and 171 aneurysms were detected. One hundred forty ruptured and 31 unruptured aneurysms were included. We measured aspect ratio which aneurysmal dome distance and neck width on angiographic images. To compare the difference of size and aspect ratio between ruptured and unrupteured aneurysms, we performed statistical analysis of aspect ratio to obtain the odds ratio(OR) for risk of rupture.
RESULTS
The mean aspect ratio was 2.33+/-0.96 for ruptured aneurysms, compared with 1.71+/-0.55 for unruptured aneurysms. The difference of the aspect ratios between ruptured and unruptured groups was statistically significant (p<0.001). The odds ratio of rupture was 6.3 fold greater when the aspect ratio was larger than 2.66 compared with an aspect ratio less than 1.54.
CONCLUSION
We suggest that aspect ratio is a significant independent predictor for aneurysmal rupture. The rupture risk was increased significantly when aspect ratio increased.