What is a PET scan?
Positron emission tomography (PET) is an imaging procedure used for diagnosis. During a PET scan, pictures are taken of the distribution of sugar, which is known as glucose.

For the PET scan, a small amount of radioactive glucose is administered into a vein, and the administered material goes to the same places in the body that use glucose. In this procedure, your body is exposed to a very small amount of radiation. The PET scanner that takes the pictures of the glucose is similar in appearance to a CT scanner.

When is it used?
PET scanning is used when your doctor needs more information than regular x-rays, CT, or MRI provide. PET scanning generally is used to characterize as benign or malignant an abnormality seen on another study or to determine the distribution of tumors within the body.

How to I prepare for a PET scan?
You should not eat or drink anything for four hours prior to the PET scan. You can take oral medications with water during this time. If you are a diabetic, your blood sugar needs to be in good control (less than 200) before having the PET scan. If you need medication for pain or for anxiety during the scan and you have these medications, bring them with you.

What happens during the procedure?
When you arrive for the PET scan, a brief history of your illness will be obtained. You will then have an injection of the radioactive glucose into a vein. Approximately 45 minutes after the injection, you are placed in a reclining position on a moving table that can change your position inside the scanner. The table generally will be moved several times during your examination.

The scanning machine is detecting the radiation given off by the radioactive glucose that had been previously administered. The pictures usually take 45 minutes to one hour 15 minutes to obtain. The pictures are projected onto a TV screen and prepared for the doctor to examine. You need to plan to be in the PET area at least two hours.

What happens after the procedure?
Generally, there are no special measures to take after the procedure. You will experience no side effects from the procedure. You do not need to have someone with you for the procedure.

What are the benefits of this procedure?
The PET scan can provide your doctor with information that is not available from the other imaging procedures. It will help the doctor diagnose your problem.

What are the risks associated with this procedure?
You are exposed to a small amount of radiation that is not considered threatening to your health. Pregnant or lactating women should not have a PET scan without discussing the risk with their doctor.

When should I call the doctor?
The results of this examination will be available to your referring physician on the day of the examination.

This article is intended as a resource for patients receiving their cancer care at Duke University Hospital or Duke Clinic. It is not intended to substitute for medical advice from your health care team. If your doctor’s instructions differ from the information in this article, please talk with your doctor before making any changes.

Source: Duke Cancer Patient Education Program / Patient & Family Education Committee 8/00