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Alternative NamesChest PET scan; Lung nuclear medicine scan; Lung positron emission tomography; PET - chest; PET - lung; PET - tumor imaging
Definition Return to top
A lung positron emission tomography (PET) scan is an imaging test that uses a radioactive substance (called a tracer) to look for disease in the lungs, especially 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.
How the Test is Performed Return to top
The health care provider will inject a small amount of a radioactive material into one of your veins, usually on the inside of the elbow. The substance travels through the blood and collects in the tissues of the lungs.
You will be asked to wait nearby as the radioactive substance is absorbed by your body. This usually takes about 1 hour.
Then, you will lie down on a table that slides into a tunnel-shaped hole in the center of the PET scanner.
The PET machine detects energy given off by the radioactive substance and changes it into 3-dimensional pictures. The images are sent to a computer, where they are displayed on a monitor for the health care provider to read.
You must lie still during the PET scan so that the machine can produce clear images of your lungs.
The test takes about 90 minutes.
How to Prepare for the Test Return to top
You must sign a consent form before having this test. You will be told not to eat anything for 4 - 6 hours before the PET scan, although you will be able to drink water.
Tell your doctor if you are pregnant or think you might be pregnant.
Also tell your doctor about any prescription and over-the-counter medicines that you are taking, because they may interfere with the test.
Be sure to mention if you have any allergies, or if you’ve had any recent imaging studies using injected dye (contrast). Tell the PET center if you have diabetes and are taking insulin.
During the test, you may need to wear a hospital gown. Take off any jewelry, dentures, and other metal objects because they could affect the scan results.
How the Test Will Feel Return to top
You will feel a sharp prick when the needle with the radioactive substance is inserted into your vein. You shouldn’t feel anything during the actual PET scan.
Why the Test is Performed Return to top
Your doctor may order this test:
Normal Results Return to top
There are no problems detected in the size, shape, or function of the lungs. There are no areas in which the radiotracer has abnormally collected.
What Abnormal Results Mean Return to top
Abnormal results may be due to:
Risks Return to top
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 doesn’t last for very long in your body.
However, women who are pregnant or are breastfeeding should let their doctor know before having this test. Infants and fetuses 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 tracer. Some people have pain, redness, or swelling at the injection site.
Considerations Return to top
It is possible to have false results on a PET scan. Blood sugar or insulin levels may affect the test results in people with diabetes.
Most PET scans are now performed along with a CT scan. This combination scan is called a PET/CT.
Other tests that may be done instead of a PET scan include a gallium scan, CT scan, or MRI scan.
References Return to top
Silvestri GA, Jett J. Bronchogenic carcinoma. In: Mason RJ, Murray JF, Broaddus VC, Nadel JA. Murray and Nadel’s Textbook of Respiratory Medicine. 4th ed. Philadelphia, Pa:Saunders Elsevier; 2005:chap 44.
Gould MK, Fletcher J, Iannettoni MD, Lynch WR, Midthun DE, Naidich DP, Ost DE. Evaluation of patients with pulmonary nodules: When is it lung cancer? ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition). Chest. 2007;132:208S-130S.
Wahl RL. Imaging. In: Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa: Elsevier Churchill Livingston;2008:chap 21.
Kieninger AN, Welsh R, Bendick PJ, Zelenock G, Chmielewski GW. Positron-emission tomography as a prognostic tool for early-stage lung cancer. Am J Surgery. 2006;191:433-436.Update Date: 3/24/2009 Updated by: Benjamin Taragin, MD, Department of Radiology, Montefiore Medical Center, Bronx, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.