A lung positron emission tomography (PET) scan is an imaging test. It uses a radioactive substance (called a tracer) to look for disease in the lungs such as lung cancer.
Unlike magnetic resonance imaging (MRI) and computed tomography (CT) scans, which reveal the structure of the lungs, a PET scan shows how well the lungs and their tissues are working.
A PET scan requires a small amount of tracer. The tracer is given through a vein (IV), usually on the inside of your elbow. It travels through your blood and collects in organs and tissues. The tracer helps the doctor (radiologist) see certain areas or diseases more clearly.
You will need to wait nearby as the tracer is absorbed by your body. This usually takes about 1 hour.
Then, you will lie on a narrow table, which slides into a large tunnel-shaped scanner. The PET scanner detects signals from the tracer. A computer changes the results into 3-D pictures. The images are displayed on a monitor for your doctor to read.
You must lie still during test. Too much movement can blur images and cause errors.
The test takes about 90 minutes.
PET scans are performed along with a CT scan. This is because the combined information from each scan provides a more complete understanding of the health problem. This combination scan is called a PET/CT.
You may be asked not to eat anything for 4 to 6 hours before the scan. You will be able to drink water.
Tell your health care provider if:
Tell your provider about the medicines you are taking. These include ones bought without a prescription. Some medicines can interfere with the test results.
You may feel a sharp sting when the needle containing the tracer is placed into your vein.
A PET scan causes no pain. The table may be hard or cold, but you can request a blanket or pillow.
An intercom in the room allows you to speak to someone at any time.
There is no recovery time, unless you were given a medicine to relax.
This test may be done to:
A normal result means the scan did not show any problems in the size, shape, or function of the lungs.
Abnormal results may be due to:
Blood sugar or insulin level may affect the test results in people with diabetes.
The amount of radiation used in a PET scan is low. It is about the same amount of radiation as in most CT scans. Also, the radiation does not last for very long in your body.
Women who are pregnant or are breastfeeding should let their provider know before having this test. Infants and babies developing in the womb are more sensitive to the effects of radiation because their organs are still growing.
It is possible, although very unlikely, to have an allergic reaction to the radioactive substance. Some people have pain, redness, or swelling at the injection site. This soon goes away.
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.