Comparative Analysis Of Morphologic Characteristics Of Ruptured And Unruptured Aneurysms In Patients With Multiple Intracranial Aneurysms

Objective Previous studies identified some morphological factors associate with the rupture of intracranial aneurysms, but these studies were at risk for confounding by patient-specific risk factors. In this study, we avoided this risk and measurement error by comparing characteristics of ruptured and unruptured aneurysms in patients with both multiple intracranial aneurysms (MIA) and aneurysmal subarachnoid hemorrhage (aSAH) based on three-dimensional digital subtraction angiography (3D-DSA).Methods We reviewed retrospectively the clinical data of94cases with MIA and aSAH presented to Tianjin Huanhu hospital between Sept2011and Dec2013. We included61patients underwent3D-DSA and in which the ruptured aneurysm was identified, thus a total of61ruptured and78unruptured aneurysms were included. The characteristics of aneurysms were evaluated on3D-DSA. We collected five one-dimensional measurements [neck width (Wn), height (H), length (L), width (W), parent vessel average diameter (Dv)] and four two-dimensional indices [aspect ratio (AR), height-width ratio (HWR), bottleneck factor (BN), size ratio (SR)]. Parameters were analyzed with univariate statistical analyses for significance with respect to rupture. Receiver-operating characteristic analysis (ROC) was performed to identify the area under the curve (AUC) and optimal thresholds for each parameter. Significant parameters were further examined by multivariate logistic regression analysis. Before performing the regression, each of the variables was scaled to span a range from0to10, thereby ensuring that a unit increase in the parameter corresponds to10%of its observed range. This makes the odds ratios obtained for the variables easily comparable.Results In MIA patients with aS AH, the most common site of ruptured aneurysm was the ICA C7, but the rate of aneurysm rupture in the AComA and ACA was significantly higher than that in the other sites (P<0.05). The ruptured aneurysms were larger than the unruptured ones, which has significant difference (5.94±3.32vs3.83±2.89, P<0.05). However, there were6(9.83%) patients in which the ruptured aneurysm was not the largest one. The ruptured incidence of aneurysm in<3mm,>3 mm to≤7mm, and>7mm were20.0%,58.5%and81.0%, respectively. Although there was significant difference among these three groups (P<0.05), there are only17(27.9%) aneurysms>7mm in the61ruptured aneurysms, and aneurysms>7mm did not constitute more than one-third of all ruptured aneurysms at any given location. From the univariate statistical analyses, significant differences were found between ruptured and unruptured means for Wn, H, L, AR, BN and SR (P<0.05); W, Dv and HWR means were not significantly different (P>0.05). Multivariate logistic regression analysis further revealed that AR and SR had the strongest independent correlation with ruptured aneurysms. For a10%increase in AR and SR of an aneurysm, the odds of its rupture increase by1.34,1.45times, respectively. From the ROC analysis, AR and SR had the highest AUC values of0.78and0.81, and the optimal thresholds of1.36and1.81, respectively.Conclusions The ruptured and unruptured aneurysms in patients with both MIA and aSAH may provide an ideal study model for evaluating the association between aneurysm morphological characteristics with rupture, by avoiding the confounding bias to some extent. With regard to the high incidence of very small aneurysms in the ruptured intracranial aneurysms, the management of patients with aSAH is better performed in high-volume centers with experienced physicians. The location and size of aneurysm are associated with rupture, based on which assessing the risk of aneurysm rupture can’t reflect the morphological and hemodynamic characteristics of aneurysm well. While the AR and SR are reliable morphological indices predicting the risk of rupture. The higher the AR and SR of an aneurysm, the higher risk of rupture. But a common threshold value useful in predicting the rupture of aneurysm clinically is still not identified. In the future, the ability of the morphological parameter to predict aneurysm rupture risk need to be assessed in large prospective studies that include follow up of patients, so that it can be useful for clinicians to assess aneurysm rupture risk and make the best clinical decision ultimately.