What is a PET Scanner?

Emma Lloyd

A positron emission tomography (PET) scanner is a piece of medical diagnostic equipment that uses nuclear imaging to generate pictures of the body's interior. Nuclear imaging involves the administration of a small amount of a radioactive material to a patient who is undergoing the scan. In comparison to most other types of medical imaging equipment, a PET scanner is capable of producing the most detailed and accurate images.

A PET scan may be conducted to detect cancer.
A PET scan may be conducted to detect cancer.

This type of medical imaging has a variety of functions. In cancer treatment, it can be used to detect cancer or determine whether cancer has spread, or it can be used after treatment to determine whether the treatment has been successful. For someone who has had a heart attack, the scan can be used to determine whether any damage has been done to the heart. In addition, the scan can help pinpoint areas of cardiac insufficiency to determine whether surgery might provide any benefits. Brain abnormalities, which might include tumors, also can be evaluated using images from a PET scanner.

An PET scan utilizes special radiotracers in order to make the images clearer and easier to interpret.
An PET scan utilizes special radiotracers in order to make the images clearer and easier to interpret.

Prior to the start of the PET scanner test, a patient is given an intravenous injection of fludeoxyglucose (FDG), a type of radioactive glucose. This glucose FDG material is called a radiotracer. After the injection, the patient must lie quietly for approximately 60 minutes to allow time for the glucose to circulate through the body. After this waiting period, the patient is moved into the PET scanner for the imaging portion of the procedure.

During the 60-minute waiting period, cells in the body absorb the radioactive glucose. The PET scanning equipment is able to detect the radioactivity of the glucose, because the radioactive material emits gamma wave energy. By sensing the density of glucose in various cells of the body, the PET computer builds a three-dimensional image of the interior of the body. For example, cancer cells take up glucose at a much faster rate in comparison to healthy cells, and therefore, cancer cells appear brighter on a PET-generated image. The ability of the PET medical imaging scanner to generate three-dimensional images in high detail makes it extremely useful for disease diagnosis and prognosis.

The sensitivity and complexity of the equipment also makes it extremely expensive. A typical PET scanner costs several million US Dollars to purchase, and several hundred thousand US Dollars for annual operation and maintenance. To undergo a PET scan therefore is an expensive prospect that can cost several thousand US dollars.

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