Positron emission tomography (PET) studies of cancer with the glucose analog 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) have emerged as both a useful research and clinical method for detecting (diagnosing), staging, and monitoring treatment responses in a variety of neoplasms, including tumors of the brain, head and neck, lung, breast, gastrointestinal and genitourinary systems, lymphatic system, musculoskeletal system, and other organ systems. In addition to FDG, many other positron emitting radiopharmaceuticals are under investigation and development in oncology, but the largest set of clinically relevant results to date has been acquired with FDG. Because most aggressive neoplasms have high glycolytic rates, neoplasms throughout the body may potentially be visualized with PET, using both standard transaxial imaging methods and techniques such as whole body PET imaging for surveying the entire body.