DALLAS, April 6 – A newly developed computer program predicts the chances of brain cells dying as the result of a stroke and may refine the use of brain-saving stroke drugs, according to research reported in the April issue of Stroke: Journal of the American Heart Association.
The computer software, which uses artificial intelligence techniques, very rapidly combines several new types of images obtained by magnetic resonance imaging (MRI) into a map of the brain allowing physicians to assess the risk of brain damage with high specificity and sensitivity. “That is a major accomplishment because previously it took 20 to 30 minutes to pour through all the MRI data and determine what it all meant,” says A. Gregory Sorensen, M.D., senior author of the report, associate professor of radiology at Harvard Medical School and associate director of the nuclear magnetic resonance center at Massachusetts General Hospital in Boston. “In treating stroke, every minute is crucial in limiting permanent brain damage.”
The current standard – computerized tomographic (CT) scan – uses X-rays to generate an image of the brain to determine whether a stroke was caused by bleeding of leaky or ruptured blood vessels. If the CT scan is negative for a bleeding (hemorrhagic) stroke, it is likely that it is ischemic i.e., caused by an obstructed blood vessel. Blood clots can be dissolved by tissue plasminogen activator (tPA). The drug, however, is only recommended for use within three hours of stroke onset.
“Neurologists know that, although the rule is three hours, some people given tPA at four hours get better, and some do poorly,” says Sorensen. “All neurologists struggle with the fact that they have these guidelines for groups of patients, but they are faced with treating a single patient. They want to know how they can adapt general guidelines to the specific patient in front of them.”
That is precisely what the computer program is meant to do. “Instead of having people wade through five or eight different MRI images, we simplified this into a single risk image,” he says. “This is particularly helpful now that these new types of MRI give us such large amounts of information.”
The computer breaks the advanced MRI brain scan into tiny, distinct cubes about one-tenth of an inch in diameter. Two key pieces of information are measured for each cube. One tells whether blood flow through vessels in the area is blocked. The other indicates whether the brain tissue is living or dying. Both these types of MRI scans are advanced techniques developed in the past few years.
Combining this and other data, the computer provides an estimate of the likelihood that an area of the brain will die if not treated – say zero in one place, 50 percent in another and perhaps 90 percent in still a third.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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