Is CT or MRI the method of choice for imaging patients with acute stroke? Why should men divide if fate has united?

In the hyperacute phase of ischemic stroke, CT images are often normal or show subtle changes only. On the contrary, diffusion-weighted MRI (DWI) can reveal the ischemic lesion in its full extent within minutes only in experimental studies1 and as soon as a patient is available for imaging in clinical studies.2 As new therapeutic options for ischemic stroke have appeared3–5 and more of them are under way, having proper (and positive) imaging methods has become an essential issue. Even though most stroke physicians and neuroradiologists have recognized for years the superiority of DWI over CT in patients with acute focal neurological deficits, the work of Fiebach et al6 published in this issue of Stroke is the first to demonstrate this fact unbiasedly in a representative patient population. This work, coming from a dedicated stroke center, is an important addition to the accumulating evidence on the selection of imaging technique in hyperacute stroke. Patients presenting with a sudden, focal neurological deficit do not always suffer an ischemic stroke. Approximately 5% of these patients will harbor other diseases (tumors, postictal paresis, multiple sclerosis, hemiplegic migraine, transient ischemic attacks, malingering, or even hypoglycemia or liver disease) where MRI is usually far more informative than CT. Another 10% of these patients will have intracerebral hemorrhage that can easily be detected either by CT or by T2*-weighted MRI.7,8 High sensitivity and the high predictive value of MRI to ischemia help to avoid unnecessary and potentially dangerous therapeutic interventions and ensure that effective therapies will not be withheld for those who are suitable for these therapies. At least 15% of all ischemic strokes occur in the vertebrobasilar region (posterior circulation). MRI is certainly superior to CT in imaging vertebrobasilar territory. The authors6 had unfortunately excluded those patients from their study. There is little experience and even fewer evidence-based data on the optimal treatment of these patients given that almost all efficacy trials have concentrated on hemispheric infarctions. See article on page 2206