Positron Emission Tomography is a diagnostic examination that involves collecting images based on the delivery of radiation from the emission of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient. The subsequent images of the body are used to evaluate a variety of diseases.
PET scans are most often used to detect cancer and to examine the effects of cancer therapy by characterizing biochemical changes in the cancer. These scans can be performed on the whole body. Patients with lung cancer, colon cancer, cancers in the head and neck, advanced breast cancer, lymphoma and melanoma can avoid some surgeries and invasive tests by having PET scans. PET scans are 93% accurate in detecting the spread of lung cancer, compared to 63% for CT scans.
PET scans on the heart can be used to determine blood flow to the heart muscle and help evaluate signs of coronary artery disease. PET scans allow differentiation of nonfunctioning heart muscle from heart muscle that would benefit from a procedure, such as angioplasty or coronary artery bypass surgery.
PET scans of the brain are used to evaluate patients who have memory disorders of undetermined causes, suspected or proven brain tumors or seizure disorders that are not responsive to medical therapy and are therefore candidates for surgery.