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futurity_medicine 00445.txt

#Will stroke drug kill? MRI predicts with 95%accuracy A new MRI technique predicts with 95 percent accuracy which stroke victims will benefit from a clot-busting drugnd which will suffer potentially lethal brain bleeding. Researchers used standard magnetic resonance imaging as part of a new method to measure stroke damage to the blood-brain barrier. If there is too much barrier damage before intravenous medicine is administered to a stroke patient, that medicine could seep out of the bloodstream and into the brain, causing major damage. The drug tpa is given now to patients only within 4. 5 hours of a stroke onset to try to dissolve the blood clot causing the stroke without risking additional damage. A reliable tool to determine which patients can safely be treated beyond that window would allow more patients to be helped. f 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 safety and also potentially allowing us to give the drug to patients who currently go untreated, says study leader Richard Leigh, assistant professor of neurology and radiology at Johns hopkins university School of medicine. Described in the journal Stroke the new method is a computer program that lets physicians see how much gadolinium, the contrast material injected into a patient vein during an MRI scan, has leaked into brain tissue from surrounding blood vessels. By quantifying this damage in 75 stroke patients, Leigh identified a threshold for determining how much leakage is dangerous. He and his team then applied this threshold to those 75 records to determine if it could predict who had suffered a brain hemorrhage and who had not. The new test correctly predicted the outcome with 95 percent accuracy. The blood-brain barrier limits the passage of molecules from the bloodstream into the brain. Without it the brain is open to infection, inflammation, and hemorrhage. Ischemic stroke patients are at risk of bleeding into the brain when there is damage to the barrier. TIMING IS EVERYTHING In an ischemic stroke, a blood clot is stuck in a vessel, cutting off blood flow to a portion of the brain, which begins to die if the clot remains. When patients come to the hospital within a few hours of suffering an ischemic stroke, doctors quickly give intravenous tpa, hoping it will dissolve the clot without causing additional damage. In roughly 30 percent of stroke patients receiving tpa in a timely manner provides great benefit. In roughly 6 percent, however, there is already too much damage to the blood-brain barrier and the drug causes bleeding in the brain, severe injury, and sometimes death. But doctors haven known with any precision which patients are likely to suffer a drug-related bleed. In these situations, if physicians knew the extent of the damage to the blood-brain barrier, they would be able to administer treatment more safely, Leigh says. Most stroke patients, Leigh notes, don get to a hospital within the window for optimal tpa use so physicians don give them tpa. Sometimes, more aggressive treatment can be attempted, such as pulling the clot out mechanically via a catheter threaded from the groin area or by directly injecting tpa into the brain. MRI FOR EVERY STROKE PATIENT Typically, physicians do a CT SCAN of a stroke victim to see if he or she has visible bleeding before administering tpa. Leigh says his computer program, working with an MRI scan, can detect subtle changes to the blood-brain barrier that are otherwise impossible to see. If the findings hold up, Leigh says, e should probably be doing MRI scans in every stroke patient before we give tpa. The biggest obstacle in stroke treatment has always been time Leigh notes. The longer it takes for a patient to be treated, the less chance of a full recovery. An MRI scan does take longer to conduct in most institutions than a CT SCAN, Leigh concedes. But if the benefits of getting tpa into the right peoplend most importantly, protecting the wrong people from getting itutweighs the harms of waiting a little longer to get MRI results, doctors should consider changing their practice. f we could eliminate all intracranial hemorrhages, it would be worth it, he says. The National institutes of health National Institute of Neurological disorders and Stroke the National Institute on Deafness and Other Communication Disorders, and the Seton Healthcare Family supported the research. Other researchers from Johns Hopkins and from Emory University contributed to the study. Source: Johns Hopkins Universit

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