COMMENTARY—Imaging Makes New Stroke Assessments Possible

Traditionally, we have used a clock to identify patients who are eligible to receive reperfusion therapy, but now researchers are trying to extend patient eligibility with imaging. The Stanford, California, team is trying to identify good candidates for reperfusion treatment who present with acute ischemic stroke beyond the traditional time window of six hours. The researchers at Massachusetts General Hospital, Boston, and their collaborators are trying to apply a similar approach to patients who have unwitnessed strokes and so have an unknown elapsed time from the start of their stroke.

Bruce I. Ovbiagele, MD

The rationale behind the Stanford work is that some patients will have salvageable neurons beyond the traditional treatment time window and that this tissue can be identified by MR and CT perfusion imaging.

The workers in Boston and their collaborators used MR diffusion-weighted imaging to confirm that a patient had had a stroke, and then used MR fluid attenuated inversion recovery (FLAIR) to determine if the stroke had occurred within the previous four hours. If a stroke has not been going on long enough to produce a positive FLAIR image, it means that the patient is still eligible for thrombolytic therapy. This could be huge for US clinical practice because so many patients have unwitnessed strokes. We definitely need a larger efficacy study, but the results that Dr. Schwamm reported are highly encouraging.

CT is more widely available right now in US practice than is MRI, so ideally we would like to be able to use CT imaging.

—Bruce I. Ovbiagele, MD
Professor and Chairman of Neurology
at the Medical University of South Carolina in Charleston