Positron emission tomography Health Article

Definition

Positron emission tomography (PET) is a highly specialized imaging technique using short-lived radiolabeled substances to produce extremely high resolution images of the body's biological function.

Purpose

Besides being used to investigate the metabolism of normal organs, PET has also become the technique of choice to investigate various neurological diseases, including stroke, epilepsy, Alzheimer's disease, Parkinson's disease, and Huntington's disease. Various psychiatric disorders, such as schizophrenia, depression, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, and Tourette syndrome, are also imaged by PET, because these disorders have changes in specific areas of the brain. Additionally, PET scanning is a powerful research tool to detect changes or abnormalities in areas that may be difficult to visualize using other radiological procedures. In the field of mental health, a PET scan may be used when a patient seeks medical help for symptoms that could possibly be caused by a brain tumor. These symptoms may include headaches, emotional abnormalities, or intellectual or memory problems. In these cases, a PET scan may be performed to "rule out" a tumor, so that other tests can be performed in order to establish an accurate diagnosis.

PET is especially utilized in persons affected by cancer because it can detect metastatic tumors that may not be visualized by other imaging techniques. It is also being increasingly used not only as a cancer diagnostic tool, but also to help researchers 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.

Precautions

In some cases, patients may be allergic to the radioactive agents used for PET. A patient with known allergies should discuss this with their specialist before undergoing the PET scan.