Positron Emission Tomography (PET) uses small amounts of radioactive materials called radiotracers, a special camera and a computer to help evaluate organ and tissue functions. A PET scan measures important body functions, such as blood flow, oxygen use, and sugar (glucose) metabolism, to help doctors evaluate how well organs and tissues are functioning. By identifying body changes at the cellular level, PET may detect the early onset of disease before it is evident on other imaging tests.

Almost all PET scans are performed on instruments that are combined PET and Computed Tomography (CT) scanners. These scans provide images that pinpoint the anatomic location of abnormal metabolic activity within the body. The combined scans have been shown to provide more accurate diagnoses than the two scans performed separately.

Depending on the type of nuclear medicine exam, the radiotracer is either injected into the body, swallowed or inhaled as a gas and eventually accumulates in the organ or area of the body being examined. Radioactive emissions from the radiotracer are detected by a special camera or imaging device that produces pictures and provides molecular information.