Microcirculatory Collaterals Modulate Ischemic Core Heterogeneity on Diffusion-Weighted Imaging.

BACKGROUND AND PURPOSE: Endovascular thrombectomy (EVT) is an effective treatment for acute ischemic stroke due to large vessel occlusion (AIS-LVO). The ischemic core is best determined on DWI, which is commonly thresholded for automated analysis using ADC maps. However, there may be substantial heterogeneity in ADC values within the ischemic core. We determined how tissue-level collaterals, measured by hypoperfusion intensity ratio (HIR) on cerebral perfusion imaging, influences ischemic core heterogeneity. MATERIALS AND METHODS: We performed a post hoc analysis of the CT Perfusion to Predict Response to Recanalization in Ischemic Stroke Project 2 (CRISP 2) study of patients with AIS-LVO who underwent baseline CT/CTP and follow-up MRI/MR perfusion (MRP) prior to EVT. Patients were dichotomized into favorable (HIR ≤0.5) and unfavorable (HIR >0.5) groups, and variability in ADC reduction was determined across an ischemic core defined by standard thresholds of ADC ≤620 × 10-6 mm²/s. RESULTS: = .003) at the comprehensive stroke center. CONCLUSIONS: Favorable tissue-level collaterals (low HIR) are associated with reduced ischemic core ADC heterogeneity.