Positron emission tomography, also called PET imaging or a PET scan, is a diagnostic examination that involves the acquisition of physiologic images based on the detection 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 human body developed with this technique are used to evaluate a variety of diseases.
PET scans are used most often 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. PET scans of the heart can be used to determine blood flow to the heart muscle and help evaluate signs of coronary artery disease. PET scans of the heart can also be used to determine if areas of the heart that show decreased function are alive rather than scarred as a result of a prior heart attack, called a myocardial infarction. Combined with a myocardial perfusion study, 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, which would reestablish adequate blood flow and improve heart function. PET scans of the brain are used to evaluate patients who have memory disorders of an undetermined cause, suspected or proven brain tumors or seizure disorders that are not responsive to medical therapy and are therefore candidates for surgery.
The radiation exposure of PET-CT scanning is very low, exposing patients to no more radiation than some x-ray procedures. Tracers have been routinely used for decades without negative reactions or serious side effects. Pregnant women and nursing mothers are cautioned and advised to talk with their doctor or medical professional before having a PET-CT test, as radioactivity can pass from mother to developing fetus or to nursing infants through breast milk. After the exam, the radioactivity dissipates quickly and leaves no detectable trace after 24 hours.
Extra care and planning are also required for patients with diabetes and hypoglycemia (low blood sugar), because of the sugar-based radiotracer. These conditions don’t necessarily exclude patients from having a PET-CT scan, however, they do require special consideration and individualized instruction.
In addition to the radiotracer, some procedures may require the use of contrast agents. Allergic reactions to contrast agents are infrequent and are generally mild, usually hives and itchiness. On rare occasions, allergic reactions can be serious. Patients with a history of heart problems, diabetes or kidney disease should tell their doctors. Also inform your doctor about any allergies you may have, especially if you have had a prior allergic reaction to contrast agents.
Once obtained, your PET-CT image remains an electronic file. Florida Hospital has the most sophisticated network, viewing stations and software for processing, transmitting, reviewing and storing these electronic images.
One of our physicians, a specialist in nuclear medicine, will examine and interpret the scan and create a report of his/her findings that will be sent to the referring physician. The referring physician will present the results and discuss them with the patient.