Abstract TP84: Agreement Between Alberta Stroke Program Early Computed Tomography Score and Computed Tomography Perfusion in Patient Selection for Mechanical Thrombectomy After Large Vessel Occlusion Acute Ischemic Stroke

Abstract

Introduction: CT ASPECTS and CT Perfusion (CTP) are used to select patients for mechanical thrombectomy, an evidence-based treatment for Large Vessel Occlusion (LVO) Acute Ischemic Stroke (AIS). However, discordant results between the two imaging modalities creates uncertainty with respect to the volume of ischemic and infarcted brain tissue, and thus whether to offer revascularization. We sought to investigate the agreement between CT ASPECTS and CTP in selecting patients for mechanical thrombectomy. Hypothesis: CT ASPECTS determined by a neuro-radiologist demonstrates moderate agreement with CTP in selecting patients with anterior circulation, LVO AIS for mechanical thrombectomy. Methods: Over a 7-month period beginning in January 2018, we conducted a retrospective analysis from a large healthcare system’s stroke network database comparing the agreement between favorable CT ASPECTS (defined as score ≥ 6) and favorable CTP. Favorable CTP was defined according to the inclusion criteria from EXTEND-IA, DEFUSE 3, and DAWN, in the 0-6 hour, 6-16 hour, and 6-24 hour time windows, respectively, for patients with ICA or proximal MCA occlusions. Results: Cases were identified in the 0-24 hour window with an ICA or M1 occlusion, baseline CT ASPECTS calculated by a neuro-radiologist, and CTP. The overall raw agreement between CT ASPECTS and CTP for the 145 cases in the 0-6 hour window was 81%, and Cohen’s kappa (κ) was 0.17 (no agreement). In the 6-16 hour window, the overall raw agreement for 46 cases was 78% (κ = 0.38, minimal agreement). In the 6-24 hour window, the overall raw agreement for 58 cases was 53% (κ = 0.14, no agreement). Conclusions: In both early and extended time windows, CT ASPECTS and CTP demonstrate minimal to no agreement beyond chance in patient selection for mechanical thrombectomy. Additional studies are required to determine the most appropriate imaging selection criteria to guide treatment decisions in patients with anterior circulation, LVO AIS.