MRI Analysis Could Prevent Brain Damage From Stroke

Researchers reported in the November 2006 issue of the journal Annals of Neurology that new magnetic resonance imaging (MRI) techniques can discriminate between stroke patients who are likely to benefit from a stroke medication--even when administered beyond the currently approved three-hour time window--and those for whom treatment is not likely to be beneficial and may cause harm.

For years, Greg Albers, M.D., professor of neurology and neurological sciences at the Stanford University School of Medicine (Sanford, CA, USA; www.stanford.edu) and director of the Stanford Stroke Center, has been using new MRI techniques to visualize the damage from stroke while it is occurring. His goal is to differentiate brain tissue that is potentially salvageable from tissue that is already irreversibly injured by a stroke. As his group gathered MRI scans of stroke patients, they observed patterns that seemed to identify which patients were most likely to benefit from opening up blocked blood vessels.

To answer these questions, the investigators devised a study to see if obtaining an MRI profile from stroke patients before starting treatment could identify which patients would benefit from clot-dissolving drugs administered between three and six hours after stroke onset and which patients were unlikely to benefit, or potentially might be harmed. Dr. Albers was the lead investigator of the three-year study, which was funded by U.S. National Institutes of Health (Bethesda, MD, USA) and included sites in the United States, Canada, and Belgium.

Approximately 85% of strokes are caused by clots blocking blood vessels in the neck or brain. In 1996, the clot-busting drug tissue-plasminogen activator (tPA) was approved by the U.S. Food and Drug Administration (FDA). The drug was found to restore blood flow to regions of the brain injured by stroke. The study that led to its approval indicated that tPA should be used only in patients who were treated within three hours of the onset of stroke symptoms and who also had a computed tomography (CT) scan indicating there was no bleeding in the brain.

This is the first study to show that specific MRI patterns predict a very good response upon opening the blood vessel and that for other patterns, opening the vessel may have no beneficial effect or can even cause harm. A 20-minute MRI scan has the potential to indicate who is likely to benefit and who is not. "By having this additional information available, we should be able to make a much more sophisticated decision about which therapies are optimal for an individual patient, especially as you get into the longer time windows,” stated Dr. Albers.




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