A positron emission tomography (PET) is an imaging test that looks at the tissues and organs in the body on a cellular level. The scan uses a special dye that has radioactive tracers. The positrons emitted by these tracers are detected with a special camera during the PET scan. The camera produces three-dimensional images of the inside workings of the body. The scan is often used alongside a CT or MRI scan.
The PET scan can help identify a variety of conditions, including cancer, heart disease, and brain disorders. It can also show doctors how an organ is functioning. The results from the PET scan can help diagnose certain health conditions and plan treatment.
During the scan, you will be exposed to small amounts of radiation. This radiation is small and is not a threat to your health. Allergic reactions to the radioactive tracer are rare. Be sure to tell your doctor if you are allergic to any medicines, contrast dyes, or iodine.
Be sure to talk to your doctor if you are pregnant or think you may be pregnant. You should also consult with your doctor if you are breastfeeding.
If you are undergoing chemotherapy, be sure to let your healthcare provider know. You may have to wait a few weeks after your last chemotherapy treatment before you can have a PET scan.
If you are taking medicines, such as insulin, be sure to let your doctor know. Some medicines can interfere with the results of the PET scan. You may need to stop your medicine several hours before the PET scan.
A PET scan is very helpful in finding the source of many diseases, such as cancer. The scan can also help monitor the progression of a disease. It can also give doctors important information about heart and nervous system diseases.
Before the PET scan, your healthcare provider will explain the procedure. Be sure to listen to the instructions carefully. Your doctor may ask you to:
- Fast (not eat) for several hours before the procedure.
- If you are diabetic, you may be asked to fast for a longer period of time.
- If you using insulin, you will be given specific instructions on when to take your insulin the day of your PET scan.
- You will have a blood glucose test before your procedure.
- Drink water before your scan to keep your body hydrated.
- Avoid caffeine, alcohol, or tobacco for at least 24 hours before your scan.
The PET scan is an outpatient procedure. If you are a patient in the hospital, it may be performed during your stay. For the PET scan, you will:
- Sign a consent form when you arrive. Be sure to bring photo ID and your insurance information.
- Wear a hospital gown. This will be provided to you for the procedure.
- Remove jewelry and watches.
- Empty your bladder before starting the procedure.
- Have an intravenous (IV) line placed in a vein in your arm or hand. This may cause some discomfort. The radioactive tracer will then be injected into the IV. The body’s organs and tissues will absorb the tracer once it is injected. You may be asked to drink a bottle of water that contains a medicine called contrast.
- Relax in a quiet room for 45 to 60 minutes while the tracer is absorbed by the body.
- Lie on a table inside the imaging machine. The table will move you to different positions in the imaging machine. Using a scanner, the machine will detect the radiation given off by the radioactive tracer. The scan takes about 15 to 25 minutes.
Once the scan is complete, you will be asked to carefully sit up. The IV will then be removed.
A doctor called a radiologist will review the results from your PET scan. The radiologist will then send the results to your healthcare provider. You will schedule a follow-up appointment a few days after your PET scan to go over the results with your doctor.
Drink plenty of fluids for 24 to 48 hours after the test to flush out the radioactive tracer from your body.