Noninvasive Assessment of Plaque Deposits
May Help Determine a Patient's Stroke Risk
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Patient with large calcified plaque involving internal carotid artery. A. Multiplanar reconstructed MDCT image showing large degree of calcified plaque (arrow) with narrowed lumen (line). B. Mulitplanar reconstructed MDCT images used for volume measurements demonstrating cross-section of internal carotid artery with corresponding lumen (asterisk) and calcified plaque (arrow). |
Published in the March edition of Stroke, the study looked retrospectively at the composition of plaque deposits in the carotid arteries of 102 patients treated at UVa. Its findings suggest that, in determining who is most likely to have a stroke, physicians may want to take a closer look at the type of plaque building up in their patients' arteries.
According to Dr. Christopher Kramer, a professor of Radiology and Medicine at UVa and study team member, risk assessments for stroke have traditionally focused on the degree to which arterial plaque has constricted blood flow. "You might say, we've been worried about the size of the river channel," he explains. "This study and others like it indicate we also need to pay attention to the river bank and to the kind of silt that's accumulating there."
Using computed tomography (CT) angiogram images from UVa's patient database, the researchers measured calcified and noncalcified plaque in carotid arteries as well as total plaque volume. The study shows that patients with plaque that is more than 45 percent calcified had a low risk of having preceding symptoms of stroke or transient ischemic attack (TIA).
"We found that it's the proportion, rather than the percent blockage, of calcified plaque that is associated with stability in patients with narrowed arteries," Dr. Kramer notes.
The UVa researchers believe that improved risk assessments for stroke will lead to better decisions about when to intervene surgically.
The study included images taken with multidetector computed tomography (MDCT) a promising method for evaluating atherosclerotic plaque because of its high resolution and ability to assess calcium. Since it is noninvasive, MDCT may be a safe yet effective screening tool for patients with significant blockages to determine who would benefit from preventive surgery.
Leader of the UVA study was Dr. Kiran Nandalur, who is continuing his training at the University of Michigan Health System. In addition to Dr. Kramer, the research team consisted of Dr. Andrew Hardie, Dr. Prashant Raghavan and Dr. Erol Baskurt of UVa and Matthew Schipper, PhD. of the University of Michigan Health System.