A radioactive agent first pioneered in the 1960s for the purpose of detecting bone cancer can be applied to highlighting the build-up of calcium deposits in arteries, a condition that can provoke heart attack and stroke, researchers at the University of Cambridge, in collaboration with the University of Edinburgh, have shown.

The finding could help diagnosis of these conditions in at-risk patients and lead to the development of new medicines.

Professor David Newby, of the Centre for Cardiovascular Science, University of Edinburgh, explains:

“Hardening, or ‘furring’, of the arteries can lead to very serious disease, but it’s not clear why the plaques are stable in some people but unstable in others. We need to find new methods of identifying those patients at greatest risk from unstable plaques.”

Researchers injected patients with sodium fluoride tagged with a very small amount of a radioactive tracer. Using a combination of positron emission tomography (PET scan) and computed tomography (CT scan), the researchers were able to follow the progress of the tracer as it moved around the body.

Study leader Dr Anthony Davenport, from the Department of Experimental Medicine and Immunotherapeutics at the University of Cambridge, says:

“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. In fact, this new emerging technique is the only imaging platform that can non-invasively detect the early stages of calcification in unstable atherosclerosis.”

After the sodium fluoride scans, patients underwent surgery to remove calcified plaques.

The extracted tissue was imaged, this time at higher resolution, using a laboratory PET/CT scanner and an electron microscope. This verified that the radiotracer accumulates safely in areas of active, unstable calcification whilst avoiding surrounding tissue.

Dr James Rudd, a cardiologist and researcher from the Department of Cardiovascular Medicine at the University of Cambridge adds:

“Sodium fluoride is a simple and inexpensive radiotracer that should revolutionise our ability to detect dangerous calcium in the arteries of the heart and brain. 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.”

Journal reference:

Identifying active vascular microcalcification by 18F-sodium fluoride positron emission tomography Nature Communications 6, Article number: 7495 DOI: 10.1038/ncomms8495

Photo: Imaging atherosclerotic calcification or ‘hardening of the arteries’ using positron emission tomography. Credit: University of Cambridge

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