The technique can predict, with 95 percent accuracy, which stroke victims will benefit from intravenous, clot-busting drugs and which will suffer potentially lethal bleeding.
 

In a new report in the journal Stroke, the Johns Hopkins team said the new method uses standard magnetic resonance imaging (MRI) scans to measure damage to the blood-brain barrier that protects the brain from drug exposure. As a result, it could lead to more precise use of intravenous tPA, a drug that is currently limited to patients who are within 4.5 hours of a stroke onset, in order to have the best chance of dissolving the blood clot causing the stroke without risking additional damage.
 

"If we are able to replicate our findings in more patients, it will indicate we are able to identify which people are likely to have bad outcomes, improving the drug's safety and also potentially allowing us to give the drug to patients who currently go untreated," said lead researcher Richard Leigh, M.D., an assistant professor of neurology and radiology at the Johns Hopkins University School of Medicine.
 

Leigh's technique was tested on 75 stroke patients and correctly predicted the outcome with 95 percent accuracy.
 

In about one in three stroke victims, receiving tPA in a timely manner provides great benefit.

But in about 6 percent of stroke patients there is already too much damage done to the blood-brain barrier, and the drug causes bleeding in the brain, severe injury, and sometimes death.
 

If the new findings hold up, Leigh said, "We should probably be doing MRI scans in every stroke patient before we give tPA."
 

The study was funded, in part, by the National Institutes of Health.