The future success of radioimmunotherapy (RIT) lies in building relationships between oncologists and nuclear medicine physicians. Communication between these specialists is key to the progress of radioimmunotherapy, and a team approach is required among all those involved in the process, not only for the benefit of the patient, but also for the success of research endeavors. Identification of the key questions regarding diagnosis and management of cancer must be formulated to design appropriate clinical trials incorporating radioimmunotherapy. The use of imaging modalities to conduct radiotracer studies may provide valuable information with regard to drug delivery and target specificity. One such approach is positron emission tomography (PET), a functional imaging modality with high sensitivity and specificity for tumor detection. The recent addition of hybrid PET/computed tomography, enabling biologic and anatomic whole-body imaging to be performed in one examination, has further facilitated the assignment of biologic abnormalities to anatomic structures. The most widely used radiotracer for PET is 18 F-fluorodeoxyglucose; however, fluorodeoxyglucose is a relatively nonspecific tracer. Novel, more specific tracers are being designed to assess cell proliferation. Radiolabeled non-catabolized derivatives of thymidine that are incorporated into cellular DNA are undergoing clinical trials for diagnostic efficacy using PET. In vivo anatomic micro-imaging technologies, such as microPET, microcomputed tomography, and micro-magnetic resonance imaging, enable the assessment of metabolism, cell communication, and gene expression in animal models. Fast-tracking imaging methods through translational research to human use is critical if imaging is to aid in the delivery of optimal cancer treatments. This article presents an overview of the way in which imaging may facilitate the evaluation of new treatment modalities to advance patient treatment and care.