Background: We developed a simplified ABC/2-derived method to estimate total subarachnoid hemorrhage volume (SAHV) on noncontrast computed tomography in patients with aneurysmal SAH and compared the clinical and radiographic outcomes.
Methods and results: In this retrospective observational cohort study, we analyzed 277 patients with SAH admitted to our Comprehensive Stroke Center between 2012 and 2022. We derived a mathematical model (model 1) by measuring SAH basal cisternal blood volume using an ABC/2-derived ellipsoid formula (A=width/thickness, B=length, C=vertical extension) on head noncontrast computed tomography in 5 major SAH cisternal compartments. We compared model 1 against a manual segmentation method (model 2) on noncontrast computed tomography. Data were analyzed using logistic regression analysis, t test, receiver operator characteristic curves, and area under the curve analysis. There was no significant difference in cisternal SAHV analysis between the 2 models (P=0.14). Mean SAHV by the simplified method was 7.0 mL (95% CI, 5.89-8.09) for good outcome and 16.6 mL (95% CI, 13.49-19.77) for poor outcome. Patients with delayed cerebral ischemia had higher SAHV, with a cutoff value of 10 mL.
Conclusions: Our simplified ABC/2-derived method to estimate SAHV is comparable to manual segmentation and can be performed in low-resource settings. Higher total SAHV was associated with worse outcomes and higher risk of delayed cerebral ischemia. A potential dose-response relationship was observed, with SAHV >10 mL predicting worse outcomes and higher risk of DCI.
Keywords: ABC/2‐derived volumetrics; aneurysmal subarachnoid hemorrhage; clinical outcomes; delayed cerebral ischemia; subarachnoid hemorrhage volume.