Novel Models for Identification of the Ruptured Aneurysm in Patients with Subarachnoid Hemorrhage with Multiple Aneurysms.

BACKGROUND AND PURPOSE: In patients with SAH with multiple intracranial aneurysms, often the hemorrhage pattern does not indicate the rupture source. Angiographic findings (intracranial aneurysm size and shape) could help but may not be reliable. Our purpose was to test whether existing parameters could identify the ruptured intracranial aneurysm in patients with multiple intracranial aneurysms and whether composite predictive models could improve the identification. MATERIALS AND METHODS: We retrospectively collected angiographic and medical records of 93 patients with SAH with at least 2 intracranial aneurysms (total of 206 saccular intracranial aneurysms, 93 ruptured), in which the ruptured intracranial aneurysm was confirmed through surgery or definitive hemorrhage patterns. We calculated 13 morphologic and 10 hemodynamic parameters along with location and type (sidewall/bifurcation) and tested their ability to identify rupture in the 93 patients. To build predictive models, we randomly assigned 70 patients to training and 23 to holdout testing cohorts. Using a linear regression model with a customized cost function and 10-fold cross-validation, we trained 2 rupture identification models: RIMC using all parameters and RIMM excluding hemodynamics. RESULTS: The 25 study parameters had vastly different positive predictive values (31%-87%) for identifying rupture, the highest being size ratio at 87%. RIMC incorporated size ratio, undulation index, relative residence time, and type; RIMM had only size ratio, undulation index, and type. During cross-validation, positive predictive values for size ratio, RIMM, and RIMC were 86% ± 4%, 90% ± 4%, and 93% ± 4%, respectively. In testing, size ratio and RIMM had positive predictive values of 85%, while RIMC had 92%. CONCLUSIONS: Size ratio was the best individual factor for identifying the ruptured aneurysm; however, RIMC, followed by RIMM, outperformed existing parameters.

Differences in Morphologic and Hemodynamic Characteristics for "PHASES-Based" Intracranial Aneurysm Locations.

BACKGROUND AND PURPOSE: Several recent prospective studies have found that unruptured intracranial aneurysms at various anatomic locations have different propensities for future rupture. This study aims to uncover the lack of understanding regarding rupture-prone characteristics, such as morphology and hemodynamic factors, associated with different intracranial aneurysm location. MATERIALS AND METHODS: We investigated the characteristics of 311 unruptured aneurysms at our center. Based on the PHASES study, we separated and compared morphologic and hemodynamic characteristics among 3 aneurysm location groups: 1) internal carotid artery; 2) middle cerebral artery; and 3) anterior communicating, posterior communicating, and posterior circulation arteries. RESULTS: A mixed model statistical analysis showed that size ratio, low wall shear stress area, and pressure loss coefficient were different between the intracranial aneurysm location groups. In addition, a pair-wise comparison showed that ICA aneurysms had lower size ratios, lower wall shear stress areas, and lower pressure loss coefficients compared with MCA aneurysms and compared with the group of anterior communicating, posterior communicating, and posterior circulation aneurysms. There were no statistical differences between MCA aneurysms and the group of anterior communicating, posterior communicating, and posterior circulation aneurysms for morphologic or hemodynamic characteristics. CONCLUSIONS: ICA aneurysms may be subjected to less rupture-prone morphologic and hemodynamic characteristics compared with other locations, which could explain the decreased rupture propensity of intracranial aneurysms at this location.