Measuring Size Ratio using 2D imaging as a predictor of rupture risk for Intracranial Aneurysm in Southern Gauteng

Abstract

Background: The most common cause of non-traumatic subarachnoid hemorrhage (SAH) is the rupture of an intracranial aneurysm (IA). Ruptured IAs are associated with high morbidity and mortality, with approximately 50-60% of patients succumbing to the initial hemorrhage. Prophylactic treatment of unruptured IAs is often performed to prevent rupture; however, these interventions carry significant risks. Accurate risk stratification between rupture risk and treatment risk is crucial for patient management. Traditional predictors of IA rupture include size and location, but recent studies suggest that size ratio (SR) might be a more reliable predictor. Objective: This study aims to evaluate the predictive value of SR for IA rupture in a patient population from Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) and Chris Hani Baragwanath Academic Hospital (CHBAH) using 2D angiographical images. Methods: We analyzed 151 patients with a total of 172 IAs (126 ruptured, 46 unruptured) from January 2016 to December 2021. We compared SR between ruptured and unruptured IAs to determine the predictive value of SR for IA rupture risk. Results: Unruptured IAs with a SR < 2 were 78.3%, while ruptured IAs with a SR > 2 were 98.4%. The mean SR was significantly higher in ruptured IAs (3.69 ± 1.8) compared to unruptured IAs (1.93 ± 1.1; P < 0.001). Logistic regression analysis showed an odds ratio of 3.45 for doubling the SR value (P < 0.05; 95% CI: 1.045- 10.762). SR >2 demonstrated a sensitivity of 98.4%, specificity of 78.3%, positive predictive value (PPV) of 92.5%, and negative predictive value (NPV) of 94.7% for predicting rupture risk. The Wilcoxon rank-sum test confirmed that SR was statistically significant (P < 0.05). Conclusion: SR is emerging as a useful tool in predicting IA rupture risk. By focusing on the IA's size relative to the parent vessel, SR offers a more precise risk estimate than size alone, holding potential for personalized IA management. For SR to become a standard in practice, large-scale studies and cross-disciplinary collaboration are essential. This advancement represents a step towards individualized treatments, tailoring interventions to the unique vascular characteristics of each patient.