Atherosclerosis – where fatty calcium deposits clog up arteries and reduce blood flow and oxygen supply – can lead to heart attacks and strokes. Now, a team says it is possible to identify the early stages of this process on a noninvasive imaging system thanks to an inexpensive, repurposed radioactive agent.
In Nature Communications, researchers from the universities of Cambridge and Edinburgh in the UK, describe how they used a radioactive agent that was first developed in the 1960s to detect bone cancer to highlight the build-up of unstable calcium deposits in patients’ arteries.
Study leader Dr. Anthony Davenport, of the department of medicine at Cambridge, says this “new emerging technique is the only imaging platform that can noninvasively detect the early stages of calcification in unstable atherosclerosis.”
He and his colleagues expect the technique – which uses sodium fluoride tagged with a tiny amount of radioactive tracer – will help diagnose atherosclerosis and develop new drugs to treat it.
There are several ways atherosclerosis can be dangerous. One way is that the gradual build-up of fatty deposits (known as “plaques”) gradually harden and narrow the artery wall, eventually restricting blood flow and oxygen supply.
Another way that atherosclerosis can be dangerous is that in some cases, pieces can break off from the calcium deposits. If that happens in an artery that supplies the brain or the heart, it can cause a blockage that results in stroke or heart attack.
While it is clear that atherosclerosis can lead to very serious disease, what is not so clear is which people will develop the unstable plaques that allows pieces to break off – so the earlier they can be identified, the better the chances that early treatment will save lives.
For their study, the team injected patients with the radiotracer version of sodium fluoride (18F-NaF).
Then, using a combination of imaging techniques (positron emission tomography and computed tomography, or PET/CT), they tracked the tracer as it moved around the body.
“Sodium fluoride is commonly found in toothpaste as it binds to calcium compounds in our teeth’s enamel,” Dr. Davenport explains, “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.”
After undergoing the scans, the patients had surgery to remove the plaques in their arteries. The researchers then examined them at a higher resolution using a laboratory PET/CT scanner and an electron microscope.
This detailed examination confirmed that the 18F-NaF tracer builds up in areas of active, unstable calcium deposits, and not in surrounding tissue.
Co-author, Dr. James Rudd, a cardiologist and researcher at Cambridge, says 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. He concludes:
“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.”
Most of the funds for the study came from the Wellcome Trust, supplemented with contributions from the British Heart Foundation, Cancer Research UK and the Cambridge NIHR Biomedical Research Centre.
In February 2015, Medical News Today learned how researchers are working on a way to get nanomedicines to treat atherosclerosis. Writing in Science Translational Medicine, a Harvard-led team describes how they developed nano-sized “drones” that deliver targeted drugs and repair arteries. The tiny particles were small and sticky enough to push their way under the calcified deposits and effect repair.