A positron emission tomography (PET) scan is a special king of imaging test which allows doctors to see how certain tissues and organs within the body are functioning. The most significant difference between a PET scan and other imaging tests such as MRI or CT scan is the ability to detect changes in the body at the cellular level rather than after a disease has progressed enough to actually effect the surrounding tissue or organs. A PET scan may be useful for helping to detect certain types of cancer, brain disorders, heart problems, and other conditions of the central nervous system.

A PET scan is performed by injecting a small amount of radioactive chemical into a vein. As the chemical travels through the body, it is absorbed by the organs and tissues. During the test, a scanner records the energy produced by the cells. A computer converts the recording into three-dimensional pictures of an area of the body and any cells that are changing show up at a brighter contrast to any surrounding, normal cells.

There is very little preparation involved prior to a PET scan and they are most often done on an outpatient basis. In general, most patients are simply given restrictions on food or drink for 6 to 12 hours prior to the test. Heart patients, diabetics, and other specific patients may be given a specific set of directions depending on the purpose of the PET scan. The test takes approximately 2 hours to complete.

PET scan technology is widely used in oncology as it helps to stage and detect certain types of cancer including breast cancer, lymphoma, and certain types of lung cancer. PET scan technology is also widely used in medical research.

Due largely to the technology and equipment involved, a PET scan is considerably more expensive than conventional imaging tests. Most insurance plans will cover a PET scan if certain conditions apply. Before undergoing a PET scan, patients should check with their insurance company about coverage benefits and requirements.