Estimation of Wall Thickness in Middle Cerebral Artery Aneurysms Using Fluid-Structure Interaction Simulations

Patient‐specific modeling of vessel wall thickness remains a key challenge in Fluid–Structure Interaction (FSI) simulations of cerebral aneurysms. To address this gap, the authors introduce the “aneurysm‐OSI‐band” (AOB)—derived from the Oscillatory Shear Index (OSI)—as a marker of localized wall thickness. Moreover, this study provides a direct comparison of OSI calculations against intraoperative imaging, offering confirmation of the AOB approach. In addition, FSI convergence is improved with an optimized residual method. A total of 25 Middle Cerebral Artery (MCA) aneurysms treated at a single institution between 2016 and 2020 were retrospectively analyzed. Digital subtraction angiography (DSA) data were used for FSI simulations and OSI calculation. The resulting OSI maps were systematically compared with intraoperative images, wherein thin‐ and thick‐walled regions were identified macroscopically. This correlation enabled statistical comparison and assessment of the accuracy of the AOB in localizing distinct wall‐thickness profiles. Defining the AOB based on OSI values revealed a statistically significant distinction between thin‐ and thick‐walled aneurysm segments. Quantitative analysis demonstrated robust concordance between simulation‐derived OSI patterns and intraoperative observations, highlighting OSI value differences between thin and thick-walled areas. The introduction of the AOB provides a method for assessing patient‐specific wall thickness and determining rupture status. These findings underscore the potential of advanced computational modeling to improve personalized aneurysm management and enhance clinical outcomes.