Abstract 129: An Automated Perfusion Collateral Score as a Tool to Predict Inter-Hospital Infarct Growth and Functional Outcome

Abstract

Background: The accuracy of infarct growth prediction based on collateral scores, assessed on CT perfusion (CTP) and CT angiography, has been modest. We aimed to investigate the accuracy of infarct growth prediction using a novel collateral score based on two CTP parameters. Methods: Patients were included from CRISP2, a multi-center prospective cohort study of stroke patients with an anterior circulation large vessel occlusion who are transferred from a primary stroke center (PSC) to a comprehensive stroke center (CSC). CTP was performed at the PSC, and MRI was performed immediately after arrival at the CSC. The inter-hospital infarct growth rate was calculated as the difference between the co-registered infarct volumes on MRI and CTP divided by the time interval between the scans, with fast inter-hospital growth ≥ 5ml/h. The hypoperfusion intensity ratio (HIR) was defined as the ratio of the volumes of Tmax >6s and Tmax >10s, and the CBV index as the ratio of mean CBV values within the Tmax >6s volume and the mean CBV in normal brain regions. An automated collateral score, based on the HIR and CBV index, was calculated from the CTP images at the PSC ( Fig 1A ). Results: Of 183 patients who were included, 111 (61%) were classified as having good collaterals and 72 (39%) as poor. Patients with poor collaterals experienced more rapid early infarct growth (median 2.19 ml/h IQR [0.32, 5.46] vs 7.92 [4.23, 16.23]; p-value <0.001) and had worse 90-day functional outcomes (p=0.01). The combined collateral score, based on both HIR and CBVindex, showed a trend towards better prediction of fast infarct growth compared to HIR alone (HIR ≥ 0.40 = poor collaterals) and CBV alone (CBVindex < 0.85 = poor collaterals) ( Fig 1B ). Conclusion: A perfusion collateral score, based on HIR and CBV index, is strongly associated with inter-hospital infarct growth rate and functional outcome. This automated tool can aid in patient selection for (neuroprotective) treatment strategies and transfer decisions.