The Relationship Between Characteristic Geometry And Risk Of Rupture In Cerebral Saccular Aneurysms

Object: To explore the relationship between the characteristic geometry and the risk of rupture by evaluating the depth, neck width and aspect ratio in ruptured and unruptured cerebral saccular aneurysms.Methods: Through retrospective study on the clinical data of 473 patients undertaking cerebral angiography from August 2001 to December 2007, and measurement of the depth, the neck width and the aspect ratio(AR) which was calculated from the depth divided by the neck width. All patients were divided into two groups: The ruptured and the unruptured. We did statistical analysis of all data by SPSS 13.0, and tried to figure out the relationship between the characteristic geometry and the risk of rupture.Results: There were 426 ruptured and 47 unruptured aneurysms. The mean depth, neck width and the aspect ratio(AR) was 5.9mm, 3.0mm and 2.1 for ruptured aneurysms, compared with 8.0mm, 4.2mm and 1.7 for unruptured aneurysms. These differences were statistically significant (P <0.01).Conclusions: This study shows that even aneurysms smaller than 10 mm may have high risk of rupture. Among aneurysms with the same depth measurement, the one with the wider neck measurement is less likely to rupture. AR reflects the geometrical and hemodynamic feature of cerebral saccular aneurysms very well. The high aspect ratio may be useful in predicting imminent aneurysmal ruptures. But by now, no definitive aspect ratio is accepted in discriminating between unruptured and ruptured aneurysms.