Territorial CT Perfusion Burden and Outcome After Aneurysmal Subarachnoid Haemorrhage: A Retrospective Single-Centre Cohort Study

Background: Delayed cerebral ischaemia remains a major cause of secondary brain injury after aneurysmal subarachnoid haemorrhage (aSAH). Although computed tomography perfusion (CTP) is widely used for vasospasm surveillance, perfusion abnormalities are commonly reported only as present or absent, potentially overlooking the prognostic relevance of their extent. We investigated whether a territory-based perfusion burden score is associated with outcome more closely than binary perfusion deficit assessment. Methods: This retrospective single-centre cohort study included 179 patients with aSAH who underwent at least one CTP examination during hospitalization. CTP was performed according to clinical indication rather than at predefined time points; 448 examinations were evaluated. Two blinded neuroradiologists assigned one point per affected vascular territory (score range 0–12), and the maximum score during hospitalization was analysed. Outcomes were functional outcome at 6 months (modified Rankin Scale 0–2 versus 3–6), new cerebral infarction at discharge, and in-hospital mortality. Multivariable logistic regression models were built by forward selection from prespecified covariates (age, Hunt and Hess grade, modified Fisher grade, intracerebral haemorrhage, external ventricular drainage, and aneurysm treatment modality). Results: Territorial perfusion burden was independently associated with poor functional outcome (adjusted odds ratio 1.17 per point, 95% confidence interval 1.02–1.33) and new cerebral infarction (adjusted odds ratio 1.36 per point, 95% confidence interval 1.19–1.55). Any perfusion deficit was associated with new infarction (odds ratio 8.88, 95% confidence interval 3.31–23.87) but not with functional outcome. Conclusions: In this selected cohort under CTP surveillance, the extent of perfusion impairment was associated with functional outcome and infarction, whereas binary deficit assessment was associated with infarction only. These preliminary findings suggest that territorial perfusion burden may refine risk stratification, but prospective validation with standardized imaging time points is required before the score can be used as a prognostic tool.