Rupture Resemblance Models May Correlate to Growth Rates of Intracranial Aneurysms: Preliminary Results

Background: Treatment of intracranial aneurysms (IAs) is largely guided by IA size and growth. Preliminary investigations have found a relationship between clinical factors and growth; yet, the relationship between morphologic and hemodynamic risk prediction models in IA growth is unknown. Methods: We analyzed serial images of 5 growing and 6 stable IAs. Rupture resemblance scores (RRSs) were calculated from three-dimensional segmented images and computational fluid dynamics simulations. The morphologic (RRS_M), hemodynamic (RRS_H), and combination (RRS_C) scores leveraged IA size ratio, wall shear stress, and oscillatory shear index. Comparisons of RRS and morphologic and hemodynamic characteristics were made between growing and stable IAs at the baseline time point and between the baseline and follow-up time points of the growing IAs. In addition, we investigated the correlation of growth rate and RRS and the hemodynamics of growing and stable regions were compared. Results: Our results indicate that there is no statistical difference in IAs at the baseline time point; however, growing IAs tend to have a higher aspect ratio (P = 0.066), undulation index (P = 0.086), and RRS_C (P = 0.86). In addition, we found a significant correlation between growth rate and baseline RRS of all 3 models (RRS_M, r = 0.874, P < 0.001; RRS_H, r = 0.727, P = 0.011; RRS_C, r = 0.815, P = 0.002). We also found that growing IAs significantly increased in aspect ratio (P = 0.034), size ratio (P = 0.034), and RRS_M (P = 0.034). Our results show that stable and growing regions had statistically different wall shear stress and oscillatory shear index. Conclusions: Based on this preliminary study, we conjecture that aneurysms that resemble ruptured IAs may grow faster.