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Nuclear Medicine/PET Scanning

What is positron emission tomography (PET)?

Positron emission tomography (PET) is a type of nuclear medicine procedure that measures metabolic activity of the cells of body tissues.

Since PET is a type of nuclear medicine procedure, this means that a tiny amount of a radioactive substance, called a radiopharmaceutical (radionuclide or radioactive tracer), is used during the procedure to assist in the examination of the tissue under study. Specifically, PET studies evaluate the metabolism of a particular organ or tissue, so that information about the physiology (functionality) and anatomy (structure) of the organ or tissue is evaluated, as well as its biochemical properties. Thus, PET may detect biochemical changes in an organ or tissue that can identify the onset of a disease process before anatomical changes related to the disease can be seen with other imaging processes such as computed tomography (CT) or magnetic resonance imaging (MRI).

Before the procedure

  • You may be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
  • Notify the radiologist or technologist if you are allergic to latex and/or sensitive to medications, contrast dyes, or iodine.
  • Fasting for a certain period of time prior to the procedure is required, usually for at least four hours. Your doctor will give you special instructions ahead of time as to the number of hours you are to withhold food and drink. Your doctor will also inform you as to the use of medications prior to the PET scan.
  • Notify your doctor if you are pregnant or suspect you may be pregnant.
  • Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
  • You should not consume any caffeine or alcohol, or use tobacco, for at least 24 hours prior to the procedure.
  • If you are a diabetic who uses insulin, you may be instructed to take your preprocedure insulin dose with a meal three to four hours prior to the procedure. Your doctor will give you specific instructions based on your individual situation. Also, a fasting blood sugar test may be obtained prior to the procedure. If your blood sugar is elevated, you may be given insulin to lower the blood sugar.
  • Based on your medical condition, your doctor may request other specific preparation.

During the procedure

PET scans may be performed on an outpatient basis. Procedures may vary depending on your condition and your doctor's practices.

Generally, a PET scan follows this process:

PET Scan

  1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.
  2. If you are asked to remove clothing, you will be given a gown to wear.
  3. You will be asked to empty your bladder prior to the start of the procedure.
  4. One or two intravenous (IV) lines will be started in the hand or arm for injection of the radionuclide.
  5. In some cases, an initial scan may be performed prior to the injection of the radionuclide, depending on the type of study being done. You will be positioned on a padded table inside the scanner.
  6. The radionuclide will be injected into your vein. The radionuclide will be allowed to concentrate in the organ or tissue for about 30 to 60 minutes. You will remain in the facility during this time. You will not be hazardous to other people, as the radionuclide emits less radiation than a standard X-ray.
  7. After the radionuclide has been absorbed for the appropriate length of time, the scan will begin. The scanner will move slowly over the body part being studied.
  8. When the scan has been completed, the IV line will be removed.

While the PET scan itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure, such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

After the procedure

You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.

You will be instructed to drink plenty of fluids and empty your bladder frequently for 24 to 48 hours after the test to help flush the remaining radionuclide from your body.

The IV site will be checked for any signs of redness or swelling. If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this may indicate an infection or other type of reaction.

Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

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