PET/CT scan

The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on April 27, 2021.

What is a PET/CT scan?

This advanced nuclear imaging technique combines a positron emission tomography scan (PET) and computed tomography scan (CT) into one machine. The combination of CT and PET imaging reveals information about both the structure and function of cells and tissues in the body during a single imaging session.

During a PET/CT scan, a technologist gives the patient an intravenous injection of glucose (sugar) solution that contains a very small amount of radioactive tracer for most imaging. Other radioactive agents may be used depending on your cancer type. The radioactive material travels through the bloodstream to the areas of the body with unusual metabolic activity, including any organs or tissues with primary cancer or metastasis.

During the nuclear medicine scan, the patient rests on a table and slides into a large, tunnel-shaped scanner. The PET/CT scanner is then able to "see'' damaged or cancerous cells where the glucose/radiotracer mixture is being taken up (cancer cells often use more glucose than normal cells) and the rate at which the tumor is using the glucose (which may help determine the tumor grade in some tumors). This helps stage your tumor by determining which parts of the body have abnormal activity. The outpatient procedure is painless and varies in length, depending on the part of the body being evaluated.

By combining information about the body's anatomy and metabolic function, a PET/CT scan provides a more detailed picture of cancerous tissues than either test does alone. The PET and CT images appear in a single scan, allowing for a high level of accuracy. Compared to an X-ray or magnetic resonance imaging (MRI scan), this imaging test enables doctors to examine medical conditions and abnormalities at a cellular level. The use of PET/CT scan helps the oncology team develop the optimal cancer treatment plan. Follow-up may involve additional testing and biopsy or treatment protocols, such as radiation therapy and chemotherapy.

Many oncologists perform a CT scan and/or a bone scan prior to ordering a PET/CT scan.