Computed Tomography Perfusion in Acute Ischemic Stroke: Is It Ready for Prime Time?

Abstract

### David S. Liebeskind, Mark W. Parsons, and Max Wintermark Computed tomography perfusion (CTP) is beyond prime time, ready for use to select patients with acute ischemic stroke for intravenous and endovascular reperfusion therapies in routine clinical practice. After 2 decades of fervent stroke research using advanced imaging and revascularization techniques, recent stroke trials astutely combined imaging and therapeutic expertise, likely the recipe for their resounding success. Multimodal CT, including CTP, was a key element in these trials that selected individuals with favorable collateral profiles and resultant improved outcomes after effective reperfusion.1 Academic discourse about optimal thresholds of ischemic core and mismatch volumes comprise late news, beyond prime time. Literature of only a few years ago aptly predicted the pivotal role of CTP.2 Lev2 eloquently noted the impact of collateral perfusion, critical data from a snapshot of hemodynamics, and the essential imaging goals of delineating core to avert hemorrhage while measuring salvageable tissue at-risk that need not be perfect. Prior trials failed to leverage advanced imaging or alternatively, entwined imaging and reperfusion inefficiently. In 2015 and beyond, triage of acute ischemic stroke for potential reperfusion should rapidly and efficiently identify optimal candidates for thrombolysis and thrombectomy across the broadest population. Multimodal imaging can swiftly address ischemic injury in the brain, arterial occlusion, collateral status, and the topography of perfusion that map the risk of hemorrhagic transformation and nutritive reperfusion. As noted by Lev,2 multimodal imaging is brain and may improve outcomes and optimize costs. The stroke community has historically been polarized between minimalists and extremists regarding the role and nature of imaging for acute stroke evaluation. Minimalists have argued that noncontrast CT may suffice; yet this approach will no longer work in the endovascular era when presence/absence and location of arterial occlusion and collateral profile are pivotal. In addition, telemedicine supplant refutes the minimalists’ argument that …