Radiology: Volume 251: Number 3—June 2009
Max Wintermark, MD Howard A. Rowley, MC Michael H. Lev, MD
As outlined by Kohrmann and Schellinger in their pro magnetic resonance (MR) imaging article, the two primary goals of acute stroke imaging are to distinguish ischemic stroke from intracranial hemorrhage (ICH) and to select ischemic stroke patients for reperfusion therapies. In this article, we too will focus on ischemic stroke imaging. Although our focus remains on nonhem-orrhagic stroke with respect to the advantages of advanced computed tomography (CT) over advanced MR imaging in stroke evaluation in all comers, we wish to underscore that CT angiography is becoming increasingly important in the evaluation of patients with ICH, as it has the ability to depict underlying vascular malformations, such as aneurysms, that could warrant immediate surgery. Moreover, the detection of active contrast material extravasation at CT angiography (the recently described spot sign) also has predictive value with regard to both hematoma growth (1,2) and mortality (3). This spot sign has the potential, in future clinical trials, to be used to select patients with ICH who are eligible for factor Vila therapy. To our knowledge, there is no MR counterpart for the CT angiography spot sign. Also, MR studies can be difficult to perform in patients with ICH, as they are often critically ill and require mechanical support and intensive monitoring; furthermore, there is a need for extremely rapid assessment and triage, given the potential risks of herniation, intracranial hypertension, and death. CT remains an available, affordable, and— for stroke triage—accurate modality.