Purpose: Ischemic stroke patients with low cerebral blood volume (CBV), low apparent diffusion coefficient (ADC) and increased microvascular permeability (K2) have increased risk of parenchymal hemorrhage (PH) after recanalization therapies. We have developed a predictive model to examine the risk of PH following revascularization therapies using combined MR perfusion and diffusion biomarkers.
Methods: Voxel-based values of rCBV, K2, and ADC from the infarction core were obtained using pre-treatment MRI data from patients enrolled in the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) clinical trial. Using histogram analyses the 10th and 90th percentile values were calculated for the rCBV, ADC, and K2 variables for each patient. The associations between PH and extreme values of CBV (10%rCBV), ADC (10%ADC), and K2 (90%K2) in each patient were assessed in univariate and multivariate analyses. Receiver operating characteristic (ROC) analysis was performed to determine the optimal parameter/s and threshold for predicting PH.
Results: In 83 patients included in this analysis, 20 (24%, 13 PH1, 7 PH2) developed PH. Univariate analysis showed significantly lower 10%rCBV and 10%ADC values and significantly higher 90%K2 values in patients with PH. After controlling for age, baseline NIHSS, infarct volume, and status of recanalization, multivariate logistic regression analysis identified 10%rCBV (p=0.002) and 90%K2 (p=0.03), but not 10%ADC (p=0.07), as independent predictors of PH. For 10%RCBV, ROC analysis showed the greatest AUC (0.87) at a threshold < 0.45 with sensitivity/specificity of 95%70%. For 90%K2, the greatest AUC (0.75) was obtained at a threshold of > 0.27 with sensitivity/specificity of 90%/60%. In a separate model, a combined K2-rCBV classifier remained the single independent predictor of PH (OR=33).
Conclusion: Our results suggest that combined increased permeability and decreased rCBV derived from MR perfusion can be used for risk stratification in patients with AIS before undergoing revascularization therapies.