MRI Can Identify Who May Benefit From Stroke Rx

Stroke patients who will respond best to clot busting medication may be determined by MRI

(RxWiki News) Clot-dissolving stroke medication can save lives if given within hours of a stroke. A new method may help pinpoint those who are most helped and those most harmed by this treatment.

Tissue plasminogen activator (tPA) is the only therapy for ischemic strokes (those caused by a clot) approved by the Food and Drug Administration, but it must be administered within three hours or up to 4.5 hours in certain patients. The faster the treatment is delivered, the better the chances are for recovery.

In some patients, tPA can cause deadly bleeding in the brain. Using a new imaging technique, doctors may now be able to identify stroke patients most likely to benefit from tPA and those most likely to sustain damage to the brain.

"If experiencing stroke symptoms, get medical attention right away."

Richard Leigh, MD, an assistant professor of neurology and radiology at the Johns Hopkins University School of Medicine in Baltimore, Maryland, led this investigation on the use of MRI scanning to evaluate harm to the blood-brain barrier and predict potential bleeding in the brain.

The blood-brain barrier consists of cells that line blood vessels in the brain and prevent foreign substances from passing outside the bloodstream where they can hurt the brain.

In about 6 percent of those who have an ischemic stroke, there is too much damage done to the blood-brain barrier, and the use of tPA causes bleeding in the brain, severe injury and sometimes death.

Dr. Leigh and his team looked at MRI scans of 75 stroke patients and assessed how much gadolinium leaked into the brain tissue from surrounding blood vessels during an MRI. Gandolinium is the contrast material injected into a patient to perform an MRI scan.

All the patients had received tPA within the 4.5-hour window and most (68) received tPA therapy within the recommended three-hour timeframe.

Based on the MRI scans, the researchers could determine the threshold for how much leakage was dangerous.

The scientists came up with a computer model that predicted with 95 percent accuracy a limit of gandolinium leakage that would correspond to having a brain hemorrhage (excessive bleeding).

This method has the potential to show physicians the extent of damage to the blood-brain barrier from a clot so they can more safely administer treatment, according to Dr. Leigh.

Currently, stroke victims typically receive a CT scan before tPA to determine bleeding. Dr. Lee said that his MRI technique may detect subtle changes to the blood-brain barrier that a CT scan may miss.

While he admitted that MRI can take longer than CT to administer, he said in a press release, "If we could eliminate all intracranial hemorrhages, it would be worth it.”

Dr. Leigh is now weighing information on patients who received stroke therapy beyond the standard time limit for treatment — in some cases, hours outside of the cutoff. He said that it’s possible that some people who come to the hospital many hours after a stroke can still benefit from tPA.

“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 Dr. Leigh.

This study's results were reported online in May in the journal Stroke.

The research was supported by grants from the National Institute of Neurological Disorders and Stroke, the National Institute on Deafness and Other Communication Disorders, and the Seton Healthcare Family.

Review Date: 
May 23, 2014