Abstract WMP13: The Predictive Value of Volumetric MRI Profiles in Stroke Patients Receiving IV tPA in the 3-Hour Time Window

Abstract

Background: Recent studies have detected a population of acute ischemic stroke patients whose MRI profile is associated with intracranial hemorrhage (ICH) when treated beyond 3 hours. This so-called malignant profile (MP) supports MRI based selection of patients for treatment. Purpose: To test the hypothesis that there is an MRI based volumetric profile that identifies patients at increased risk of ICH when treated with IV tPA within 3 hours Methods: An analysis was performed on a database of stroke patients provided by the STIR and VISTA Imaging Investigators. 75 patients were identified who had DWI, PWI, and GRE images prior to IV tPA and follow-up imaging to assess for parenchymal hematoma (PH). The pre-tPA MRI scans were analyzed using Matlab software to calculate DWI and PWI volumes. DWI lesions were defined by an ADC threshold of 600. PWI lesions were defined by a time-to-peak threshold of an 8 seconds delay. Follow-up GRE images were reviewed for evidence of PH. ROC curves were generated using thresholds from 1-300mL. Results: 44 of the 75 patients were women with a mean ± stdev age of 70±17. The mean NIHSS was 12±9. The mean time from stroke onset to tPA administration was 147±30 minutes. For the entire cohort, mean lesion volumes were 22±41mL for DWI and 41±42 mL for PWI. 9 patients developed PH. For the PH group, mean lesion volumes were 24±20 mL for DWI and 48±40 mL for PWI. The ROC curves are shown in Figure 1. The areas under the curves are 0.68 for DWI volumes and 0.60 for PWI volumes. The optimal thresholds for predicting PH were 13 mL for DWI with a sensitivity of 0.67 and a specificity of 0.66 and 21 mL for PWI with a sensitivity of 0.78 and a specificity of 0.46. Conclusions: Although DWI volume performed better than PWI volume in predicting PH, neither served as a robust predictor in this population. Although further studies are needed, these results suggest that an MRI profile defined by DWI and PWI volumes in the 0-3 hour window may not be able to reliably guide clinical management.