Molecular imaging comprises a range of techniques, spanning not only several imaging modalities but also many disease states and organ sites. While advances in new technology platforms have enabled a deeper understanding of the cellular and molecular basis of malignancy, reliable non-invasive imaging metrics remain an important tool for both diagnostics and patient management. Furthermore, the non- invasive nature of molecular imaging can overcome shortcomings associated with traditional biological approaches and provide valuable information relevant to patient care. Integration of information from multiple imaging techniques has the potential to provide a more comprehensive understanding of specific tumor characteristics, tumor status, and treatment response.