Metal‐Based Imaging Agents

Abstract

Radiopharmaceuticals are drugs that contain a radionuclide and are routinely used for diagnosis and treatment of disease. This review discusses imaging agents that are useful for diagnosis using Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). Moreover, this entry focuses on the growing class of metal‐based imaging agents, wherein the radionuclide is a transition metal or posttransition metal. The most widely used radionuclide for radiopharmaceuticals is technetium‐99m, 99m Tc, owing its widespread availability from the parent–daughter generator and its excellent physical properties for imaging. The radionuclides 67 Ga, 111 In, 210 Tl, 57 Co, and 51 Cr are used in the clinic as well. There are a number of radioisotopes, including 64 Cu, 67 Cu, 68 Ga, that show promise for diagnostic purposes. An increased understanding of the coordination chemistry of 99m Tc and other radiometals resulted in first‐generation metal‐essential imaging agents. This understanding of coordination chemistry is responsible for the introduction and development of targeted receptor‐specific agents, many of which are in clinical trials and some of which are on the market.