Molecular imaging with single photon emission computed tomography

With the emergence of the new field of molecular imaging, there is an increasing demand for the development of sensitive and safe novel imaging agents that can be rapidly translated from small animal models into patients. Nuclear medicine 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. The focus of this article will be to review the novel molecular imaging-based contrast agents that have the greatest potential for use as radiopharmaceuticals for single photon emission computed tomography (SPECT) imaging. We will discuss how these new tracers - particularly when coupled to CT or magnetic resonance imaging (MRI) - can be employed in the noninvasive study of a number of human diseases in the nuclear medicine clinic in near the future.