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  • Carotid Artery MRI Improves Risk Assessment for Cardiovascular Disease

    Radiology research compares ultrasound and MRI in measuring carotid artery wall thickness

    October 9, 2018

    Images show common carotid artery (CCA) wall thickness assessment in a 62-year-old man by using, A, ultrasound and, B, MRI. 

    MRI measurements of wall thickness in the carotid arteries improve cardiovascular disease risk assessment, according to a new study in the journal Radiology.

    Research has shown that plaque buildup in the carotid arteries often mirrors that in the coronary arteries, but the carotids are more easily imaged, making them potentially useful vessels for assessing the risk of strokes, heart attacks and other adverse cardiovascular events.

    Researchers compared ultrasound (US) measurements of intima-media thickness (IMT), the most widely used imaging method to assess early carotid atherosclerosis, with vessel wall MRI, a promising, noninvasive technique. While US measurements of IMT are usually based solely on views of the artery’s far wall, MRI can also see all three layers of the artery, including the adventitia, which might be important for defining vascular inflammation.

    “High-resolution MRI can tell us the stage of plaque in the wall and tell us about plaque features that could lead to stroke,” said study lead author Bruce A. Wasserman, MD, from Johns Hopkins University School of Medicine in Baltimore.

    Results Surprising to Researchers

    From July 2000 to December 2013, the researchers enrolled 698 men and women from the Multi-Ethnic Study of Atherosclerosis (MESA), a major, long-running project involving six research centers around the U.S. Study participants ranged in age from 45 to 84 years old with a mean age of 63 at first visit and no known history of cardiovascular disease. The participants underwent US and MRI between 2000 and 2004 to compare carotid artery wall thickness. During subsequent follow-up, the researchers looked for any correlation between carotid artery wall thickness measurements and coronary heart disease and stroke.

    When included simultaneously in the same model, MRI wall thickness — but not IMT — remained associated with outcomes, according to results.

    “What we saw was surprising,” Dr. Wasserman said. “MRI measures of carotid artery wall thickness were more consistently associated with cardiovascular events than was intima-media thickness using ultrasound. This tells us that perhaps MRI could be a better predictor of cardiovascular events, especially stroke.”

    Results showed that MRI wall thickness measurement with gadolinium-based contrast enhancement was more strongly associated with stroke compared with non-contrast MRI measurement. The adjusted hazard ratios for coronary heart disease, stroke and cardiovascular disease associated with per standard deviation increase in IMT were 1.10, 1.08 and 1.14, respectively. The corresponding associations for mean wall thickness measured with proton-density–weighted MRI were 1.32, 1.48 and 1.37; corresponding associations for mean wall thickness measured with gadolinium-enhanced MRI were 1.27, 1.58 and 1.38.

    Further Research Planned

    Dr. Wasserman cautioned that more research is needed to define how much MRI can add to the predictive models currently in use. MRI is expensive and would be impractical as a stand-alone measure of cardiovascular risk, but it could have a role in providing critical supplementary information for some patients.

    “We’ve come a long way with MRI techniques and their ability to discriminate the carotid artery wall and assess adventitia thickness,” he said. “Ultrasound has also improved, and we want to be able study cardiovascular risk and carotid artery thickness using these contemporary techniques.”

    Further studies are planned with the newer technology and in larger population groups.


    Images show common carotid artery (CCA) wall thickness assessment in a 62-year-old man by using, A, ultrasound and, B, MRI. 

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