Blood-Brain Barrier Permeability Assessed by Perfusion CT Predicts Symptomatic Hemorrhagic Transformation and Malignant Edema in Acute Ischemic Stroke

A 75-year-old woman was admitted to the emergency department with a right hemiparesis. She underwent stroke CT imaging work-up approximately 2 hours after symptom onset. NCCT revealed no evidence of intracranial hemorrhage, and she was treated with IV tPA at this time. Twenty-three hours later, she was in critical condition in the intensive care unit, and imaging follow-up at that time demonstrated development of PH-2. There are 2 red arrows—1 on the admission permeability map and 1 on the follow-up NCCT. The red arrows indicate that the patient presented with a “hotspot” (a sizable volume of abnormally elevated permeability on the baseline PCT study); this hotspot was centered in the same place as a focus of significant hemorrhage in the patient's eventual PH-2. Of note, permeability hotspots (voxels with absolute permeability >5 mL/100 g/min that are delineated in blue automatically by the software) occur in both the infarct and penumbra, not just in the infarct, where the vasculature has presumably undergone the most severe ischemia-induced damage. Thus, permeability imaging provides information above and beyond what is provided by the standard PCT parameters that can be used to define infarct and penumbra.