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Imaging & Radiology

Baylor University Medical Center at Dallas

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Positron Emission Tomography(PET) or PET/CT 

What is a PET/CT Scan?

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A PET/CT scan is a highly advanced medical imaging tool. Positron emission tomography (PET) shows your body’s metabolic activity, while the computed tomography (CT) shows your anatomy or body structures.

When combined, the PET and CT scans show what’s happening inside your body, including both normal and abnormal metabolic activity, as well as the anatomic details of the area where the normal and abnormal activity is taking place. A PET/CT scan is most often used to detect and locate a variety of common cancers, to determine if and where a cancer has spread or if it has responded to therapy. PET/CT scans are also used to assess neurological conditions, such as Alzheimer's dementia, or certain cardiac conditions. This information can help your doctor better understand what is happening inside your body and discuss with you the most effective next steps.

What happens during a PET/CT Scan?

A PET/CT scan is a non-invasive and painless procedure. Depending on the type of scan, it can be performed in about 90 minutes. Afterward, you may resume your normal activities, such as driving.

To start the process of your PET/CT scan, you will be given a fruit-flavored drink called a "contrast solution." A small amount of a radioactive sugar compound is then injected into your bloodstream. The radioactive sugar circulates in your body while you relax for approximately one hour.

As the radioactive sugar is absorbed into the blood stream, it is drawn to the most active areas of the body that need energy. These areas of energy show up as infrared color on the imaging scan and help the physician interpret the image and locate areas that could be a health concern. 

You then lie on the scanner table that slowly moves into the scanner. It’s very important that you do not move or adjust your position during this process so  the two scans can be aligned and fused together.

When the imaging procedure is complete, the scanner will send the information to a computer that both displays the PET and CT images side by side and combines the images to maximize the information obtained by the study. A radiologist who specializes in interpreting PET/CT images will review the information and provide a detailed report to your physician, who will share the results with you.

Note: The risks associated with PET/CT scanning are minimal. The radioactive sugar compound, which is commonly called FDG, is short-lived and leaves your body quickly. The radiation exposure associated with a PET/CT scan is similar to that associated with conventional imaging exams.