Introduction

Positron emission testing (PET) is a diagnostic imaging test that is used to help determine how organs and tissues inside the body are functioning. It also shows the size, shape, and position of organs. PET is used to help detect cancer and determine how far cancer has spread. It is used to identify abnormal growths and heart dysfunction. The results from PET not only help determine the course of a disease, but also aid in treatment planning. PET may be performed with computed tomography (CT) in a procedure called PET/CT.

PET is a noninvasive procedure. It uses an injected radioactive substance that is absorbed by cells. The PET machine detects the energy from the radioactive substance and converts it into images on a computer screen.

Preparation

PET is usually performed at an outpatient radiology center or the radiology department of a hospital. You will be instructed not to eat anything for 4 to 6 hours before the procedure. Tell your doctor if you are pregnant or nursing, have diabetes, or are allergic to injected contrast dye (radioactive tracer). Let your doctor know all of the medications that you take. You will receive specific preparation instructions when you make your appointment. Preparation instructions may vary depending on the area of the body that is being imaged.

You will wear a gown for the procedure. You will need to remove metal objects, such as jewelry, watches, and removable dentures before the test. You will be injected with the radioactive tracer about 30 minutes to an hour before your scan.

Procedure

You will lie on a narrow table, and your body will be positioned by the technician. The table will glide into the PET scanner. You will be instructed to remain motionless while the images are taken. The scan is painless and may last from about 15 minutes to an hour, depending on the particular procedure.

A radiology technician may perform your test, but is not qualified to diagnose or discuss your condition or results with you. A radiologist or your doctor will review your results with you.