MRI Test May Prevent Stroke Risk

High-resolution magnetic resonance imaging (MRI) can identify patients with clogged carotid arteries who need immediate surgery to avoid a stroke, according to a study conducted by researchers at the University of Washington (Seattle, USA). The findings were reported in the January 15, 2002, issue of Circulation.

The core of plaque in the carotid arteries has an outside covering of fibrous tissue. This fibrous cap can be thick, thin, or ruptured. By studying the tissue, the researchers found that when the cap thins, the plaque becomes unstable and prone to rupture. If the plaque breaks or ruptures, a blood clot can form around the broken tissue, blocking blood flow and increasing the risk for stroke.

The researchers used high-resolution MRI to study the fibrous caps in the carotid arteries of 53 patients scheduled for carotid endarterectomy. They found subtle differences and were able to identify three kinds of cap: intact thick cap, intact thin cap, and ruptured cap. Only 9% of those with intact thick caps had a history of stroke or transient ischemic attack (TIA), while 50% of those with intact thin caps had a stroke/TIA history, and 70% of those with ruptured caps had a stroke/TIA history.

The researchers caution that the results of this small study need to be confirmed in a larger study before they can recommend using MRI to guide clinical decisions. "However, these early, promising results suggest that in the future it may be possible to use MRI to track the progress of atherosclerosis and to better select patients for surgical intervention,” said Chun Yuan, Ph.D., a professor of radiology at the University of Washington and the lead author.




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