COVID-19 (Coronavirus) Information
Your health and safety are our top priorities. Learn more about our COVID-19 evaluation and testing and our commitment to providing great care while maintaining the safest environment possible.
Positron emission tomography; Tumor imaging - PET; PET/CT
A positron emission tomography scan is a type of imaging test. It uses a radioactive substance called a tracer to look for disease in the body.
A positron emission tomography (PET) scan shows how organs and tissues are working.
A PET scan uses a small amount of radioactive tracer. The tracer is given through a vein (IV). The needle is most often inserted on the inside of your elbow. The tracer travels through your blood and collects in organs and tissues. This helps the radiologist see certain areas more clearly.
You will need to wait as the tracer is absorbed by your body. This takes about 1 hour.
Then, you will lie on a narrow table that slides into a large tunnel-shaped scanner. The PET detects signals from the tracer. A computer changes the signals into 3D pictures. The images are displayed on a monitor for your health care provider to read.
You must lie still during the test. Too much movement can blur images and cause errors.
How long the test takes depends on what part of the body is being scanned.
You may be asked not to eat anything for 4 to 6 hours before the scan. You will be able to drink water but no other beverages including coffee. If you have diabetes, your provider will tell you not to take your diabetes medicine before the test. These medicines will interfere with the results.
Tell your provider if:
Always tell your provider about the medicines you are taking. Let your provider know about the medicines you bought without a prescription. Sometimes, medicines may interfere with the test results.
You may feel a sharp sting when the needle with 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.
The most common use for a PET scan is for cancer, when it may be done:
This test can also be used to:
A normal result means there were no problems seen in the size, shape, or position of an organ. There are no areas in which the tracer has abnormally collected.
Abnormal results depend on the part of the body being studied. Abnormal results may be due to:
The amount of radiation used in a PET scan is about the same amount as used in most CT scans. These scans use short-lived tracers, so the radiation is gone from your body in about 2 to 10 hours. Having many x-rays, CT or PET scans over time may increase your risk for cancer. However, the risk from any one scan is small. You and your doctor should weigh this risk against the benefits of getting a correct diagnosis for a medical problem.
Tell your provider before having this test if you are pregnant or breastfeeding. Infants and babies developing in the womb are more sensitive to radiation because their organs are still growing.
Rarely, people may have an allergic reaction to the tracer material. Some people have pain, redness, or swelling at the injection site.
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. This helps find the exact location of the tumor.
Glaudemans AWJM, Israel O, Slart RHJA, Ben-Haim S. Vascular PET/CT and SPECT/CT. In: Sidawy AN, Perler BA, eds. Rutherford's Vascular Surgery and Endovascular Therapy. 9th ed. Philadelphia, PA: Elsevier; 2019:chap 29.
Meyer PT, Rijntjes M, Hellwig S, Kloppel S, Weiller C. Functional neuroimaging: functional magnetic resonance imaging, positron emission tomography, and single-photon emission computed tomography. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 41.
Nair A, Barnett JL, Semple TR. Current status of thoracic imaging. In: Adam A, Dixon AK, Gillard JH, Schaefer-Prokop CM, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 1.
Vansteenkiste JF, Deroose C, Dooms C. Positron emission tomography. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 21.BACK TO TOP
Review Date: 7/3/2020
Reviewed By: Jason Levy, MD, Northside Radiology Associates, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2021 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.