What is PET

Positron Emission Tomography (PET) is an imaging technique that provides physicians and researchers with unique information about the body's chemistry. Unlike computed tomography (CT) or magnetic resonance imaging (MRI), which primarily examine anatomy, PET allows us to visualize body function.

PET imaging requires access to a cyclotron, which produces positron-emitting elements or radioisotopes (oxygen, carbon, nitrogen, fluorine, etc.). These radioisotopes can be easily incorporated into other chemical compounds including normal body components, like oxygen (used to image blood flow) or a drug (used to visualize brain chemical systems), to make a radiopharmaceutical. For PET imaging, the patient is asked to lie on a table similar to that on a CT scanner and receives the radiopharmaceutical, which emits positrons or positive electrons. As the positrons encounter electrons within the body, a reaction occurs that produces gamma rays, which are detected by the PET scanner. Within the scanner are rings of detectors containing special crystals that produce energy when struck by a gamma ray. The scanner's electronics record these detected gamma rays and map an image of the area where the radiopharmaceutical is located. For example, if the radiopharmaceutical is a form of glucose (used to image body energy production), the PET scan will show areas where the glucose is being used in excess of the normal body needs, such as in a growing tumor. Because the radioisotope used in a PET scan is short-lived, the amount of radiation exposure the patient receives is small and about the same as a CT scan.

This is a general overview. We recently found several very good PET tutorials of the web that review this topic in more detail. If you would like more information on PET, please try theUniversity of British Columbia's PET tutorial, UCLA's PET- The Power of Medical Imageing brochure and their Let's Play PETsite, and finally the Institute for Clinical PET's tutorial.

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please click here to see the raw images from my PET scan 9 April 2001...

please click here to see an enlarged single scan...