Research Profile – Sharing Isotope Expertise

A new research network aims to reduce reliance on an isotope needed for medical imaging.

[ Back to main article ]

Researchers are well on the way to finding ways to reduce the reliance on the radioactive tracer known as technetium-99m (Tc-99m) for medical imaging.

Tc-99m is a radioactive isotope used in a wide variety of medical imaging devices to help diagnose and monitor diseases ranging from cancer to heart disease. Recent years have seen shortages of the isotope, leading to a need to find alternatives, according to Dr. Jean-Claude Tardif, professor of medicine at the Montreal Heart Institute. Shortages have led to patients worldwide unable to get needed imaging.

Tc-99m is traditionally produced in nuclear reactors, but due to a number of reactors around the world closing down, substantial shortages are likely to occur again. While new sources of Tc-99m have been developed, reducing reliance on the isotope is sensible, according to Dr. Tardif.

To do so, centres with expertise in imaging and the use of isotopes must collaborate.

"You cannot do these studies in isolated sites. Even if they are world-class, you need to put resources, sites and protocols together," says Dr. Tardif.

The newly formed Medical Imaging Trials Network of Canada (MITNEC) is a network of research sites and investigators that is now starting those sorts of collaborative projects. Funded in part by the Canadian Institutes of Health Research, it consists of over 40 sites, including 13 universities in 5 provinces.

"We put together a network that involves three medical disciplines: oncology (cancer), cardiology and neurology (brain and nerve), to conduct studies that hopefully will demonstrate the way we can reduce our reliance on technetium," he says.

The members of the network are using three key approaches in their projects.

In one, researchers are investigating whether other types of isotopes can be substituted for Tc-99m; in the second approach, they are exploring imaging techniques that do not require any isotopes; and in the third, researchers are investigating the use of Tc-99m that does not require a reactor for production. For all three of these approaches, the resulting images will be evaluated to determine if the quality is as good as, or better than, images produced using standard, reactor-based Tc-99m.

In cardiology, a multicentre study is underway which will include 450 patients who are at high risk for heart attacks. The patients will undergo the usual cardiac imaging using Single-Photon Emission Computerized Tomography (SPECT) and Tc-99m, but will also undergo imaging using technologies which do not require the use of isotopes. The project will compare the various approaches and determine whether imaging performed using other technologies is as effective as SPECT.

Another MITNEC project is examining imaging technologies used to monitor the spread of bone cancer. Researchers are now investigating whether PET scans using different sorts of isotopes can provide the same quality of imaging for these patients as scans using Tc-99m. Similarly, in neurology, MITNEC researchers will perform a study to see whether PET scans using other types of isotopes can provide good quality images to detect early signs of dementia.

Various other studies are being planned and launched too, according to Dr. Tardif.

"You cannot do these studies in isolated sites. Even if they are world-class, you need to put resources, sites and protocols together."
– Dr. Jean-Claude Tardif, Montreal Heart Institute