What is PET Imaging?

PET (Positron Emission Tomography) is a nuclear medicine procedure that produces pictures of the body's biological functions. This is important because functional change often predates structural change in tissues, such as tissue metabolism and physiologic functions.

How Does PET Work?

Positron Emission Tomography is a non-invasive, diagnostic imaging technique for measuring the metabolic activity of cells in the human body. It is useful clinically in patients with certain conditions affecting the brain and the heart as well as in patients with certain types of cancer.

PET is unique because it produces images of the body's basic biochemistry or function. Traditional diagnostic techniques, such as x-rays, CT scans or MRI, produce images of the body's anatomy or structure. The premise with these techniques is that the change in structure or anatomy that occurs with disease can be seen. Biochemical processes are also altered with disease and may occur before there is a change in gross anatomy. PET is an imaging technique that is used to visualize some of these processes that change. Even in diseases, such as Alzheimer's disease, where there is no gross structural abnormality, PET is able to show a biochemical change. PET is a very useful addition to the clinician's diagnostic toolbox, providing significant advances to traditional diagnostic methods.

A PET Scan is a simple procedure. It involves the use of a small amount of a radioactive material, similar to what is used in other nuclear medicine procedures. The radioactivity is attached or tagged to a compound that is familiar to your body. Compounds similar to glucose, water, ammonia, and certain drugs may be used. The radioactive drug is administered to the patient, usually by injection and a specially designed PET scanner images how the body processes the drug. PET has been in clinical use since the early 1990's.

Preparation for PET Exams

Performing an actual PET scan involves having the patient recline on a table that slides into the middle of an "open-air" scanner. Within the scanner are rings of detectors containing special crystals that produce light when struck by radiation. The patient is injected with a fluid called radiopharmaceutical approximately 45 minutes before the PET scan. The scanner's electronics record detected gamma rays and maps an image of the area where the radiopharmaceutical is concentrated. Since radiopharmaceutical is comprised of a chemical commonly used by the body, PET enables the physician to detect the location of the metabolic process. As an example, a post therapy or surgery PET study, using fluro-deoxyglucose (FDG) as the radioisotope, will demonstrate where glucose uptake is occurring differentiating necrotic tissue from new and recurrent tumor growth.

PET Examination preparation requirements:

• Avoid strenuous activities on the day before the PET examination. Excessive muscular activity may interfere with interpretation of your scan.
• Cancer patients need to fast after midnight or at least six hours prior to their examination with the exception of water, and you should be well hydrated.
• Cardiac patients must eat a light breakfast the morning of the PET examination.
• If you are diabetic, please bring your medication and a light snack with you. Make sure that our staff is aware of your condition ahead of time.
• Please be prepared to stay with us for approximately three to four hours.