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MRIs Can Help Predict Stroke Risk

Advanced scan shows details of neck arteries

MONDAY, Jan. 14, 2002 (HealthDayNews) -- A sophisticated new imaging technology can size up a patient's stroke risk by showing details of the neck arteries, new research shows.

An advanced form of magnetic resonance imaging (MRI) shows the nature of the fatty plaque deposits, which can break away from the artery wall and block blood flow to cause a stroke, a group led by Chun Yuan, professor of radiology at the University of Washington has found. Their study appears in tomorrow's issue of Circulation: Journal of the American Heart Association.

In an early trial, the Washington researchers used MRI scans to study the fibrous cap that coats plaque deposits in 53 patients who were scheduled for endarterectomy, an artery-clearing procedure.

"There was a clear and consistent association between the condition of the fibrous cap as seen by MRI, and the patient's clinical status," says Yuan.

The technique is in its early stages, but the ultimate hope is that it could become a routine screening test for the risk of stroke, he says.

MRI combines computer technology, radio waves and high-intensity magnetic fields to give clear images of the body's soft tissues. The Washington researchers are using technology that gives images that are more detailed.

"At the moment, it is available only in major research institutes," Yuan says.

The report describes the results of MRI scans of the carotid arteries, which feed the brain. The scans allowed the researchers to classify the plaque deposits as "intact thick," "intact thin," or "ruptured." The patients also had neurological tests to determine if they had a history of strokes or transient ischemic attacks (TIAs), brief blockages of the arteries.

Only 9 percent of the patients with intact deposits had a history of stroke or TIA, compared to 70 percent of those with ruptured deposits.

At the moment, the evaluation of plaque "is based on visibility," Yuan says. "If we can see it on the images, we call it thick. What we believe is that after a larger-scale prospective study in which we can follow the progression of patients, a quantitative measure may be established."

That study has begun, with funding from the National Institutes of Health and a goal of enrolling 300 patients. "The hope is that we can catch them before they have a stroke or TIA," Yuan says.

Advances in MRI technology could make the technique a useful diagnostic tool, he says.

"With new hardware provided by the manufacturers, we could cut the scan time until it has potential for a screening tool," Yuan says. "That's what we're after."

The MRI technology could solve "a real quandary if it could be used on high-risk patients to identify those where the benefits of endarterectomy outweigh the risk," says Dr. Larry Goldstein, director of the stroke center at Duke University School of Medicine.

"The technique may have a role if it can be used to predict who will have symptoms, and whether therapy alters the risk," says Goldstein. "Having a non-invasive way to do this would be helpful."

But the newness of the technique and the small number of patients on whom it has been used mean that a lot of research must be done to fulfill that hope, he says.

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"It is important to say that this technique offers future potential, but at this moment we can't say that patients should all go through it," Yuan says. "This is still a preliminary study."

You can learn about the risk factors and treatment for stroke from the American Stroke Association or the National Institute of Neurological Disorders and Stroke.

SOURCES: Interviews with Chun Yuan, Ph.D., professor of radiology, University of Washington, Seattle; Larry Goldstein, M.D., director, stroke center, Duke University Medical Center, Durham, N.C.; Jan. 15, 2002, Circulation: Journal of the American Heart Association
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