Abstract
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. In the early 1980s, [99mTc]Tc-Sestamibi, [99mTc]Tc-Tetrofosmin, and [99mTc]Tc-Teboroxime were approved as commercial radiopharmaceuticals for myocardial perfusion imaging in nuclear cardiology. Despite its peculiar properties, the clinical use of [99mTc]Tc-Teboroxime was quickly abandoned due to its rapid myocardial washout. Despite their widespread clinical applications, both [99mTc]Tc-Sestamibi and [99mTc]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. 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. 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. 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.
Highlights
Introduction published maps and institutional affilHeart disease is the leading cause of death worldwide
To date, [99m Tc]Tc-Sestamibi and [99m Tc]Tc-Tetrofosmin (Figure 1) are the most used for the study of ischemic heart disease. The development of these radiopharmaceuticals is due to their peculiar chemical–physical properties as well as the ease of preparation (Figure 1). [99m Tc]Tc-Sestamibi is a mono-cationic lipophilic complex formed by the coordination of six identical 2-methoxyisobutylsonitrile (MIBI) ligands to the central technetium atom in the oxidation state +1
Due to its rapid cardiac washout, imaging should be finished within 5 to 6 min of its injection. This is difficult to achieve in most clinical studies and its clinical use radiopharmaceuticals and shows better linearity (0–4.5 mL/min/g) between myocardial absorption and myocardial blood flow than that of [99m Tc]Tc-Sestamibi and [99m Tc]TcTetrofosmin [27]
Summary
To date, [99m Tc]Tc-Sestamibi and [99m Tc]Tc-Tetrofosmin (Figure 1) are the most used for the study of ischemic heart disease The development of these radiopharmaceuticals is due to their peculiar chemical–physical properties as well as the ease of preparation (Figure 1). [99m Tc]Tc-Sestamibi is a mono-cationic lipophilic complex formed by the coordination of six identical 2-methoxyisobutylsonitrile (MIBI) ligands to the central technetium atom in the oxidation state +1 It is prepared through the addition of generator eluted [99m Tc]NaTcO4 to a commercial kit containing all the reagents in freeze-dried form. The heart uptake is 1% of the injected dose after rest injection, and 1.4% after exercise injection at 1 h post intravenous injection, respectively This radiopharmaceutical rapidly clears from the blood pool [18].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
