Positron Emission Tomography (PET) is becoming increasingly important in the diagnosis and staging of many forms of cancer as well as for evaluating the effectiveness of therapy. It is currently the most optimal way to check for tumor recurrence. Cancers for which PET is considered particularly advantageous include lung, head and neck, colorectal, esophageal, lymphoma, melanoma, breast, and thyroid. The PET scan provides information about cell function in contrast to the anatomic picture yielded by conventional imaging. PET is also being employed in the neurologic evaluation of seizures and Alzheimer’s disease as well as in some cardiac patients with previous myocardial infarction who are being considered for a revascularization procedure.

PET images reveal the chemistry of organs and other tissues such as tumors. A radiopharmaceutical, most common fluorodeoxyglucose (FDG), is injected into the patient. FDG is a combination of glucose and a radionuclide (radioactive element). The latter interacts with electrons in the body to produce annihilation photons that can be recorded on the detector crystal of the PET scanner. The recorded emissions produce a three dimensional map of how glucose is used throughout the body. Cancer cells generally take up more glucose than normal cells and are consequently highlighted as brighter areas on the scan.

The most recent PET innovation is dual modality PET-CT which facilitates even more precise localization of molecular alterations of cancer tissue while simultaneously shortening scan time by at least 50%.

Related links about PET from other websites:

http://radiologyinfo.org/content/petomography.htm

http://www.intelihealth.com/IH/ihtIH?t=20755&p=~
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http://www.petscaninfo.com/zportal/portals/pat