Abstract WP44: Comparison of Multi-modal CT Imaging Protocols Used for Decision-Making on Endovascular Treatment in Patients With Acute Ischemic Stroke

Abstract

Introduction: Several CT-based imaging protocols are being used to decide on endovascular treatment (EVT) in acute ischemic stroke. Multiple scans provide extra information but expose patients to additional radiation and/or contrast. We aimed to assess the added value of a delayed phase CTA (dCTA) and CT perfusion (CTP) to non-contrast enhanced CT (NCCT) with arterial phase CTA (aCTA) by comparing treatment decisions based on five commonly used imaging protocols. Methods: We retrospectively included consecutive acute ischemic stroke patients who had a symptomatic intracranial arterial occlusion between January 2015 and November 2016 and underwent NCCT, aCTA, dCTA, and CTP. The imaging studies were grouped into five protocols: 1) NCCT and aCTA, 2) NCCT, aCTA, and CTP, 3) NCCT, aCTA, dCTA, 4) NCCT, aCTA, dCTA, and CTP, and 5) NCCT and dCTA. Two interventional neuro radiologists independently decided on the indication for EVT for each patient based on these imaging protocols in a blinded fashion. They reached consensus for discrepant decisions. We assessed the inter-rater agreement using kappa statistics, the rater’s level of confidence, followed by comparison of treatment decisions for the different imaging protocols using McNemar’s test. Results: We included 73 patients (44% male, mean age 74). The inter-rater agreement was higher for protocols with three or more modalities (κ= 0.613-0.704) compared to two-modality protocols (κ=0.506-0.529). The highest inter-rater agreement and level of confidence was achieved for the combination of NCCT, aCTA, and CTP. Adding CTP to NCCT and aCTA resulted in a 10% increase and adding dCTA in a 4% increase in the number of patients being offered EVT. These changes in management did not reach statistical significance (p=0.065 and p=0.25 respectively). Conclusion: Based on these results, adding CTP and/or a delayed phase CTA to NCCT with arterial phase CTA can assist in better patient selection for EVT in acute ischemic stroke, even though it may not significantly change management.