Rupture of vulnerable atherosclerotic plaque, which frequently occurs without prior symptoms, is responsible for a considerable number of deaths and disabilities worldwide. Identification of atherosclerotic plaques with a high risk for disruption and thrombosis would allow preventive therapy to be initiated before thrombi begin to clog arteries and cause stroke or heart attack.
The researchers, from Boston University School of Medicine (BUSM; MA, USA), studied diagnostic protocols in an animal (rabbit) model of human disease with procedures that never could have been applied to humans. Plaque disruption was stimulated at a precise time to allow MRI imaging before and after the rupture. According to researchers, plaques that were hidden within the vessel wall and pushing the vessel wall outward instead of occluding the lumen had a very high chance of forming a thrombus; plaques that caused vessel narrowing were almost always stable, which could clarify why the most lethal plaques usually escape detection by X-ray angiography.
The study's results demonstrated that accurate, noninvasive MRI can identify these stable and unstable plaques. It also reported that enhanced gadolinium uptake, which is associated with histologic findings of inflammation, tissue necrosis, and the proliferation of blood vessels in tissue not typically containing them, can predict dangerous plaque.
"The MRI exams reported are promising for application to human disease because they are noninvasive, use a clinically approved contrast agent and are performed using a clinical MRI scanner,” said lead author James A. Hamilton, Ph.D., a professor of biophysics and physiology at BUSM. "The findings suggest that MRI may be used as a noninvasive modality for localization of plaques that are prone to disruption.”
Clinical studies of carotid plaques with the reported exams from the rabbit model are ongoing in Dr. Hamilton's lab. The study's findings were published in the May 2010 issue of the journal Circulation Cardiovascular Imaging.
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