Nuclear medicine applications in molecular imaging

With the emergence of the new field of molecular imaging, there is an increasing demand for development of sensitive and safe novel imaging agents that can be rapidly translated from small animal models into patients. Nuclear medicine and positron emission tomography (PET) techniques have the ability to detect and serially monitor a variety of biologic and pathophysiologic processes, usually with tracer quantities of radiolabeled peptides, drugs, and other molecules at doses free of pharmacologic side effects, unlike the current generation of intravenous agents required for magnetic resonance (MR) and computed tomography (CT) scanning. In this article, we will review a representative sampling of the wide array of radiopharmaceuticals developed specifically for nuclear medicine radionuclide imaging that have been approved for clinical use, and those in pre-clinical trials. We will also review the existing strategies used to select the appropriate biologic markers and targets for radionuclide labeling that have been employed in the development of novel radiotracers and the imaging of small animals with new microSPECT (single photon emission computed tomography) technologies.