In order to be able to administer appropriate therapeutic regimes before irreversible myocardial damage occurs, early detection is essential. Among heart diseases, the progressive narrowing of the coronary artery due to atherosclerotic deposits, known as coronary artery disease (CAD), is a major cause of early and permanent disability. Heart disease is the leading cause of death worldwide. This short review summarizes the developments in 99mTc myocardial perfusion tracers, which are able to fulfill hitherto unmet medical needs and serve a large population of patients with heart disease, and underlines their strengths and weaknesses, the lost and found opportunities thanks to the developments of the new ultrafast SPECT technologies. Although it is difficult to reconcile all these properties in a single tracer, scientific research in the field has always channeled its efforts in the development of molecules that are able to meet the characteristics of ideality as much as possible. An ideal radiotracer for myocardial perfusion imaging should have a high myocardial uptake a high and stable target-to-background ratio with low uptake in the lungs, liver, stomach during the image acquisition period a high first-pass myocardial extraction fraction and very rapid blood clearance and a linear relationship between radiotracer myocardial uptake and coronary blood flow. Despite their widespread clinical applications, both Tc-Sestamibi and Tc-Tetrofosmin do not meet the requirements of an ideal perfusion imaging agent due to their relatively low first-pass extraction fraction and high liver absorption.

Despite its peculiar properties, the clinical use of Tc-Teboroxime was quickly abandoned due to its rapid myocardial washout. In the early 1980s, Tc-Sestamibi, Tc-Tetrofosmin, and Tc-Teboroxime were approved as commercial radiopharmaceuticals for myocardial perfusion imaging in nuclear cardiology. The favorable nuclear properties in combination with the rich coordination chemistry make technetium-99m the radioisotope of choice for the development of myocardial perfusion tracers.

Petra by T.L. Higley