Positron Emission Tomography Reveals Vascular Microcalcifications

Researchers at the University of Cambridge (United Kingdom) and the University of Edinburgh (United Kingdom) used a radiotracer version of sodium fluoride (18F-NaF) to try and to identify the process by which microcalcifications are formed in the blood vessels and build up into atherosclerotic plaque. To do so, they used electron microscopy, histology, autoradiography, and preclinical and clinical PET/CT to analyze how sodium fluoride builds up and binds to active, unstable calcium deposits.

The researchers succeeded in showing that sodium fluoride adsorbs to calcified deposits within atherosclerotic plaque with high affinity, and is selective and specific. Using the radioactive (18)F-NaF tracer, PET/CT imaging can even distinguish between areas of macro- and micro-calcification in active unstable atherosclerosis, and could thus potentially help foster new approaches to developing treatments for vascular calcification. The study was published on July 7, 2015, in Nature Communications.

“Sodium fluoride is commonly found in toothpaste as it binds to calcium compounds in our teeth's enamel. In a similar way, it also binds to unstable areas of calcification in arteries and so we're able to see, by measuring the levels of radioactivity, exactly where the deposits are building up,” said senior author Anthony Davenport, MD, of the department of medicine at Cambridge. “This new emerging technique is the only imaging platform that can noninvasively detect the early stages of calcification in unstable atherosclerosis.”

“18F-NaF is a simple and inexpensive tracer that should revolutionize the ability of doctors to detect dangerous calcium deposits in the arteries of the heart and brain,” added coauthor cardiologist James Rudd, MD. “This will allow us to use current treatments more effectively, by giving them to those patients at highest risk. In addition, after further work, it may be possible to use this technique to test how well new medicines perform at preventing the development of atherosclerosis.”

Calcification in atherosclerotic plaque is a complex process that exhibits similarities to new bone formation, representing a confluence of bone biology and chronic plaque inflammation. Since the rate of calcification is a surrogate measure for atherosclerosis progression, noninvasive detection of calcium could serve as a useful risk stratification tool.

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