Positron emission tomography is an imaging test that uses a small amount of radioactive material (radiotracer) to show how your tissues and organs are functioning. The radiotracer can be injected, taken orally, or inhaled; the method of delivery and the amount of radiotracer will depend on what organ or tissue is being studied.
A PET scan can determine blood flow, oxygen use, and sugar (glucose) metabolism. A PET scan is useful for detecting a variety of health problems including neurological problems, heart disease and cancer. The radiotracer will collect in higher concentrations in areas of the body with higher levels of chemical activity. These areas usually correspond with areas of disease and will show up brighter on the scan.
Using a method known as image fusion or co-registration the PET scan images can be superimposed over the images from a CT scan or MRI, in this way the images from two different studies can be viewed together allowing for more precise information and more accurate diagnosis. Manufactures now provide models of the PET know as SPECT/CT and PET/CT that are capable of performing two imaging studies, PET and CT scan for example.
In oncology, PET and PET CT scans can be used not only to diagnose and stage certain cancers but can also be used to gauge the early response to treatment making it possible to determine a treatment program based on individual response and identifying those who are not responding to their current treatment.
After receiving the radiotracer the patient will need to wait about 60 minutes before the actual imaging study can begin. This allows the radioactive material to circulate through the body and accumulate in the organs and tissue being studied.
Prior to having a PET scan it is important to tell your doctor about any medicines, vitamins or herbal supplements you are taking. If you are pregnant, think you might be or you are breast-feeding your baby tell your doctor, the fetus or baby may be exposed to the radiotracer. Your doctor will give you instructions on how to prepare for the scan; this will usually include not eating for several hours beforehand.
A PET scan can be performed on an out patient basis or while hospitalized depending on the circumstances. If you have a PET scan as an outpatient you will probably be asked to wait until the images have been read before leaving, this is to insure that no additional images are needed.
