Positron emission tomography (PET) is a nuclear medicine exam that produces a three dimensional image of functional processes in the body. A PET scan uses a small amount of a radioactive drug to show differences between healthy and diseased tissue. The diagnostic images produced by PET are used to evaluate a variety of diseases.
Some common uses of PET
To detect cancer
To evaluate the heart for blood flow, signs of coronary artery disease or heart function
To evaluate the brain for memory disorders, brain tumors or seizure disorders
How to prepare for this procedure
PET is usually done on an outpatient basis. You should wear comfortable clothes. You will be instructed to not eat for four to six hours before your scan. Drink plenty of water prior to your exam. Consult with your doctor regarding the use of medications before the test.
What to expect from this procedure
You will receive an intravenous (IV) injection of the radioactive substance. However for some patients, you may be asked to inhale the substance. The radioactive substance will then take approximately 30 to 90 minutes to travel through your body and be absorbed by the tissue under study. During this time, you will be asked to rest quietly and avoid significant movement or talking, which may alter the localization of the administered substance. You will be positioned on the PET scanner table and be asked to lie still during your exam. Scanning takes 30 to 45 minutes.
Some patients who are being evaluated for heart disease may undergo a stress test in which PET scans are obtained while they are at rest, and again after undergoing the administration of a pharmaceutical to alter the blood flow to the heart.
Usually, there are no restrictions on daily routine after the test. You should drink plenty of fluids to flush the radioactive substance from your body.
What to experience during the procedure
If given an intravenous injection, you will feel like a slight prick. However, you will not feel the substance in your body.
You will be made as comfortable as possible on the exam table before you are positioned in the PET scanner for the test. You will hear buzzing or clicking sounds during the exam. Patients who are claustrophobic may feel some anxiety while positioned in the scanner. Some patients find it uncomfortable to hold still in one position for more than a few minutes.