Less radiation and more accurate test for heart disease.

What is it about?

Diagnostic testing for heart disease includes myocardial perfusion imaging studies. Rather than using two doses of radioactive drugs to perform these studies, the amount of radiation patients are exposed to can be significantly reduced by using only a single dose and measuring changes in the distribution (redistribution) over time. This requires imaging patients sooner.

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Why is it important?

In 1989, several technetium-99m (Tc) isotopes were introduced for diagnostic imaging. Prior to the introduction of these isotopes most cardiac imaging was performed using thallium-201 (Tl). Tl was given as a single injection following "stress" and two sets of images were obtained to determine if the patient had coronary artery disease (CAD) or tissue damage (myocardial infarction, MI). This decision was made by comparing the first post-stress image with a second image, where the Tl had moved around (redistributed) over time. Hence, one dose of Tl, followed by two sets of images comparing the two results to make the diagnosis. With the introduction of Tc agents, physicians were told Tc did not redistribute and that two doses of the isotope would be needed. In truth, these drugs do of course redistribute, they merely redistribute much earlier than Tl. The consequence includes: (1) many patients with CAD were misdiagnosed by failing to look early enough to find the heart disease, with an estimated 100,000 possible deaths per year, (2) 3 million Curies of excess radiation have been given to patients with the clinical staff also being exposed to this additional amount. Put in perspective, the Fukushima Nuclear Reactor leaked 10 million Curies, shutting the reactor down with noticeable radiation measured in California, and (3) Tens of Billions of extra dollars of health care costs paid out by insurance companies, including CMS to pay for these additional doses of Tc.