Molecular imaging is a rapidly emerging research tool and clinical discipline aimed at noninvasive, quantitative visualization of in vivo molecular processes occurring at cellular and subcellular levels. At present, advancement of the molecular imaging field is driven by the development of improved imaging hardware for use in preclinical and clinical settings, the identification and validation of new, biologically relevant imaging targets, and the development of improved imaging probes derived from novel chemistries. Of these 3 essential facets, which comprise a majority of current molecular imaging research, hardware development and novel target discovery significantly outpace the development and clinical advancement of new molecular imaging probes, particularly with respect to cancer imaging.