Guide To Positron Emission Tomography Scans (PET Scans)

A positron emission tomography scan (PET scan) is a type of imaging test used for diagnosing numerous diseases in an individual's body. This scan highlights parts of the body where there are increased rates of certain chemical activities. A PET scan can tell a patient's doctor about how their body uses oxygen, how their body processes glucose, and about their blood flow. These scans can give a patient's doctor insight into problems occurring at the cellular level. This helps them identify and evaluate certain complex systemic conditions and diseases, including heart problems and brain disorders. Around two million PET scans are performed annually in the United States.

Individuals need these scans. As they diagnose many conditions, they are vital for receiving the necessary treatment. For instance, these scans help direct the best cancer treatment, including radiation therapy, chemotherapy, and immunotherapy for cancer. The scans show the effectiveness of the treatment as well. These scans also accurately diagnose heart conditions, helping doctors determine where surgery and medications for heart disease are appropriate. Of course, patients must understand how positron emission tomography scans work first.

How The Scan Works

A positron emission tomography scan uses a large machine with a hole in the center or a scanning device. Both will pick up subatomic particles or photons emitted by a radiotracer in the tissues or organ being examined. The radiotracer used for this scan depends on the particular tissues or organs of interest and the scan's purpose. The selected radiotracer is administered to the patient's body through a vein in their arm via an intravenous line. Once the radiotracer has been administered, the scanning part of the device slowly moves over the necessary part of the patient's body. 

As particular tissues in the body break down the radiotracer, positrons are emitted. When positrons are emitted in the body from the breakdown of the radiotracer, gamma rays are produced. The positron emission tomography scanner can pick up these gamma rays and use this information to compose an image map of the internal tissues. The higher the concentration of gamma rays, the brighter the spot will appear in the scan's image.