Size ratio: a morphological factor predictive of the rupture of cerebral aneurysm?

Abstract

BACKGROUND: Determining factors predictive of the natural risk of rupture of cerebral aneurysms is difficult. We studied morphological factors associated with rupture in a study model of patients with mirror location intracranial aneurysms, one aneurysm that had ruptured and one that had not, each patient served as their own control attempting to eliminate confounding variables. METHODS: We collected five one-dimensional measurements and four two-dimensional indices from three-dimensional rotational digital subtraction angiography images of patients in the proposed study model and explored their correlation with aneurysm rupture. Parameters were analyzed with a paired Student's t test for significance and significant parameters were further examined by multivariate conditional logistic regression analysis. RESULTS: Fifty-two patients with 52 pairs of intracranial aneurysms in a mirror location were studied. The maximum perpendicular height, neck diameter, maximum width, maximum height, aspect ratio, size ratio, and bottleneck factor were significantly associated with ruptured aneurysms on bivariate analysis. A logistic regression analysis showed that only size ratio, which was defined as the ratio of the maximal height to parent artery average diameter, is independently correlated with ruptured intracranial aneurysms. CONCLUSIONS: In a case-control study of patients with mirror location intracranial aneurysms, size ratio was identified as the unique morphological factor associate with the rupture of cerebral aneurysms.