In the last two decades, major advances have been made in understanding of cancer, its origin and its treatment. These include the elucidation of signaling events that are often dysregulated in specific cancer types, and the development and clinical use of agents that inhibit these signaling events. Despite these advances, we are far from understanding cancer in sufficient detail and scope to fully eradicate it. Imaging through the integration of the disciplines of physics, biology, chemistry, engineering, computing and medicine enhances our understanding of human disease. Non-invasive imaging technologies have significantly impacted the diagnosis and treatment of various pathologies including cancer. Technical achievements over the last decade provide the basis for the vision that the ability to monitor molecular events in living cells and subjects non-invasively, will result in the elucidation of novel signaling events that contribute to the disease process and provide a unique tool for the development of therapeutic interventions as well as imaging agents for early diagnosis of disease.