Definition of PET
Positron emission tomography (PET) is a highly specialized imaging technique using short-lived radiolabeled substances to produce powerful images of the body's biological function. PET scanning provides information about the body's chemistry not available through other procedures. Unlike computerized tomography (CT) or magnetic resonance imaging (MRI), techniques that show anatomy or body form, PET shows metabolic activity or body function.
PET has been used primarily in cardiology, neurology, and oncology. PET is used to investigate the metabolism of normal organs and has also become a commonly used technique to investigate various neurological diseases and disorders, including stroke, epilepsy, Alzheimer's disease, and Parkinson's disease. Various psychiatric disorders, such as schizophrenia, depression, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, and Tourette syndrome, are also studied with PET.
PET is especially useful in the context of cancer because it can detect metastatic tumors that might not be visualized by other imaging techniques. It is also being increasingly used not only as a cancer diagnostic tool, but also to help physicians design the most beneficial therapies. For example, it may be used to assess response to chemotherapy. PET imaging is very accurate in differentiating malignant from benign cell growths and in assessing the spread of malignant tumors. PET is also used to detect recurrent brain tumors and cancers of the lung, colon, breast, lymph nodes, skin, and other organs.