Abstract T P46: Absence of a Very Low Cerebral Blood Volume (VLCBV) Lesion Identifies Patients Who Are Unlikely to Have Hemorrhagic Transformation After Delayed Endovascular Reperfusion

Abstract

Objective: Ischemic stroke patients with areas of VLCBV on baseline imaging are at increased risk for hemorrhagic transformation following iv tPA induced reperfusion. The underlying hypothesis is that regions of low CBV are highly susceptible to reperfusion injury. We examined the DEFUSE 2 study data, and tested whether the presence of VLCBV assessed with an automated software tool predicts the risk of hemorrhagic transformation in patients treated with endovascular therapy up to 12 hours. Methods: Patients who reperfused following endovascular therapy and who had technically adequate PWI and DWI data were included. Presence of parenchymal hematoma (PH 1 or 2) was assessed blinded to clinical data by a neuroradiologist at the core lab. RAPID, a fully automated image processing program, was used for coregistration of the DWI and PWI images, removal of large vessels, processing of CBV maps, and calculation of relative CBV (rCBV) defined as a ratio of the original and the mirrored CBV maps. We first determined the rCBV threshold within the DWI lesion that had the highest area under the ROC curve (AUC) for predicting PH. We then determined the rCBV lesion volume at this threshold which best predicted PH. Results: 60 patients (82.6%) were included in this analysis, the median time between symptom onset and femoral puncture was 6.5 hours (PH vs. no PH 6.1 vs. 6.6; p = 0.5). Patients with PH and no PH had similar DWI volumes (p=0.08) and NIHSS scores (p=0.23) at baseline. Among patients who reperfused, the greatest AUC for predicting PH was present at an rCBV threshold of 0.3 (AUC 0.707). At this threshold, an rCBV volume of >0.86 ml optimally predicted PH with a sensitivity of 0.93 (95%CI 0.66 - 1.0), specificity of 0.52 (95%CI 0.37 - 0.67), negative predictive value of 0.89 (95%CI 0.71-0.98) and positive predictive value of 0.35 (95%CI 0.23-0.49). Conclusions: PH following endovascular reperfusion can be predicted with high sensitivity and high negative predictive value with an automated image processing tool. The optimal threshold for predicting PH is an rCBV(<30%) lesion volume of ≥0.86 ml. Patients with rCBV(<30%) lesions smaller than this threshold are very unlikely to suffer a parenchymal hematoma following reperfusion.