• Stroke
• CT

The current standard of care for acute ischemic stroke is intravenous recombinant tissue type plasminogen activator (rt-PA) for eligible patients who present within 3–4.5 h from stroke onset.1 ,2 There is firm evidence supporting its efficacy when administered to patients suspected of having acute ischemic stroke and without imaging evidence of intracranial hemorrhage.3 ,4 For patients with major artery occlusions the use of intra-arterial therapy has grown significantly,5 but remains controversial as clear outcome benefits have not been prospectively demonstrated despite higher rates of recanalization compared with intravenous rt-PA.6 ,7 Proper patient selection is paramount in all interventions. An integral component in this effort is identifying clinically proven imaging biomarkers.8 The foundational principle of reperfusion therapy is that timely vessel recanalization will stop the progression of cell apoptosis in the ischemic penumbra and limit final infarct size. For this reason, the focus of ischemic stroke imaging has been the physiologic characterization of the affected brain parenchyma. The ideal patient possesses a major artery occlusion, a small infarct (core), as well as a significant volume of threatened but still viable tissue (penumbra). Indeed, advanced parenchymal imaging techniques have been shown to identify patients for whom …