Introduction: Several demographic, morphological and hemodynamic factors influence the rupture of an intracranial aneurysm. The authors aim to investigate whether the morphological factors of an aneurysm in anterior communicating artery (ACOM Art) influence the rupture.

Methods: Several one-dimensional, two dimensional and three dimensional parameters were evaluated in 3D DSA. The measurements were performed in blinded fashion to determine whether the size and shape parameters influence the rupture. A total of thirty anterior communicating aneurysms (ruptured=15 and unruptured=15) were taken for analysis. Five one dimensional factors such as diameter of neck, maximum width of aneurysm, maximum height of the aneurysm and maximum perpendicular height of aneurysm and parent artery diameter were calculated. Two dimensional factors such as aspect ratio, size ratio, aneurysm angle, vessel angle, flow angle, parent daughter angle and bottleneck factor were estimated. Three dimensional parameters such as conicity index were also calculated. A pictorial representation of method of calculation has been depicted below. The standard demographic risk factors such as female sex, hypertension and smoking were also considered to match the two groups. Two-tailed independent student t-tests were used to determine the statistical difference between the morphological indices.Area under curve (AUC) was estimated in ROC curve for risk assessment analysis.

Results: Standard size and shape parameters are poor determinants of rupture of an ACOM Art aneurysm. The parent daughter angle (0.67), aspect ratio (0.56), bottle neck factor (0.55) and conicity index (0.44) found to be the most significant factors in ROC curve analysis. However the strength of association remain poor for each of them.

Conclusions: Standard morphometric parameters are not good predictors of rupture of ACOM Art aneurysms. Multifactorial analysis including complex shape indices along with hemodynamic parameters are required to determine the rupture risk.

Patient Care: -Knowledge of morphometric parameters predicting the rupture risk of ACOM Art aneurysms

Learning Objectives: -Morphological parameters are often considered to influence the rupture of intracranial aneurysm. -However simple size and shape indices are poor predictors of rupture. -Multifactorial study is required. -Complex morphological parameters as well as hemodynamic parameters need to be evaluate to estimate the rupture risk

References: 1. Raghavan M, Baoshun M, Harburgh R: Quantified aneurysm and rupture risk. J Neurosurg 102: 355-362, 2005 2. Dhar S, Tremmel M et al: Morphology parameter for intracranila aneurysm rupture risk assessment. Neurosurgery 63 (2) 2008: 185-197