Johns Hopkins researchers have developed a technique using magnetic resonance imaging to predict which stroke patients will benefit from clot-busting drugs and which could suffer serious harm from such treatments.
Tissue Plasminogen Activator (tPA) is an intravenous medication used to treat ischemic type strokes. If administered within three hours--and up to four-and-a-half hours for eligible patients--the drug may improve a victim's chances of recovering from a stroke. However, so much damage has been done to the blood-brain barrier in some patients as a result of a stroke that this treatment can cause bleeding in the brain, which is why use of the drug is limited to that time frame.
The researchers, led by Richard Leigh, an assistant professor of neurology and radiology at the Johns Hopkins University School of Medicine, engaged in the study with the idea that if physicians had a safe and reliable tool to determine which patients could be treated outside that four-and-a-half hour window, then more patients could be helped.
The study, published this month in the journal Stroke, involved the use of a computer program allowing physicians to see how much gadolinium--the contrast material injected into a patient during an MRI scan--leaks into the brain from surrounding blood vessels. The researchers quantified the damage in 75 patients and identified a threshold for determining how much leakage was dangerous.
The researchers then applied this threshold to the records of the 75 patients to determine how well it would predict who had suffered a brain hemorrhage and who hadn't. According to the researchers, use of the technique allowed them to predict the outcome with 95 percent accuracy.
"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," Leigh said in an announcement.
While physicians customarily perform CT scans to see if a patient has visible bleeding before administering tPA, Leigh said his program can detect subtle changes in the blood-brain behavior that can remain hidden. He added that if his team's findings eventually confirmed, "[w]e should probably be doing MRI scans in every stroke patient before we give tPA."