3D MRI Technique Helps Radiologists Detect High-Risk Carotid Disease

Canadian researchers have used three-dimensional magnetic resonance imaging (3D MRI) to accurately detect bleeding within the walls of diseased carotid arteries, a condition that may lead to a stroke. The results of the study suggest the technique may prove to be a useful screening tool for patients at high risk for stroke.

When major arteries are affected by atherosclerosis, fatty deposits, or plaques, accumulate on the inner lining of the vessel walls. Progression of the disease over time leads to narrowing, restricting blood flow or becoming completely blocked. Until recently, scientists believed that this narrowing, called stenosis, was responsible for most heart attacks or strokes. But new studies have identified the composition of complicated plaques as being a major cause of vascular events and deaths. These complicated plaques are characterized by surface ulcerations, blood clots and bleeding into the vessel wall.

"There's been a major change in our research,” said Alan R. Moody, F.R.C.R., F.R.C.P., from the University of Toronto (Canada). "We now know that the composition of carotid artery plaque is likely to be more predictive of future stroke events than the amount of stenosis in the vessel.”

In the study, which was published in the October 2008 issue of the journal Radiology and conducted at the Sunnybrook Health Sciences Center in Toronto, researchers performed 3D MRI on the carotid arteries of 11 patients, age 69 to 81. Complicated plaques were then surgically removed from the patients' diseased arteries and evaluated under a microscope.

The researchers found strong agreement between the lesions identified by MRI scans as complicated plaques and the microscopic analysis of the tissue samples. "With high spatial resolution 3D MRI, we are able to noninvasively analyze the tissue within the artery wall and identify small bleeds within rupture-prone plaques that may put patients at risk for future stroke,” Dr. Moody said.

According to Dr. Moody, 3D MRI is an application that is ideally suited to screen high-risk patients for complicated carotid plaques and to monitor the effects of interventions devised to slow the progress of the atherosclerotic disease. The technique is easy to perform and interpret and takes only a few minutes when added to an MR angiography study.

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