What is a PET/CT test?
PET/CT is a highly sensitive imaging technique used in oncology, cardiology, neurology and in infectious diseases. In this procedure, special equipment combines two procedures: positron emission tomography and computed tomography. By combining them, the doctor can obtain the benefits of both in one procedure. Performed at the same time on the same machine, the two scans create a more complete image than either test offers alone.
In a PET scan, radioactive sugar molecules are injected into the body. The scan shows biologic data about cellular activity.
The CT scanner takes a series of X-rays, which are combined by a computer to create an extremely detailed image of your internal organs or other parts of your body. The scan shows anatomical data.
The PET/CT scan can be performed in Tanner’s radiology department or at our outpatient imaging center. It is performed by a radiologist or radiology technologist who specializes in CT scanning and nuclear medicine.
Why did your doctor request a PET/CT test?
The information the doctor obtains from the two scans—the PET and the CT scan—are very different. However, they are complementary to each other. In cardiology, the PET scan shows areas with increased metabolic activity, while the CT scan shows detailed anatomical locations. A combination of these two images taken together enables a doctor to tell whether the high metabolic activity in an area of your heart is significant. If it is, it tells the doctor exactly where that area is. Sometimes the doctor will repeat the PET/CT to monitor the effect of treatment on a particular disease.
In oncology, a PET/CT scan is used to detect and determine the stage of a tumor—whether the tumor has spread to lymph nodes or other parts of the body—and evaluate the effectiveness of cancer treatments. The PET/CT is also used to guide some types of biopsies (the removal of a small amount of tissue for examination to determine whether cancer is present).
Immediately prior to the scan, a nurse will give you the injection or insert an IV. The IV includes the radioactive sugar and sometimes will include an iodinated dye. During the test, you’ll be asked to lie flat with your arms above your head for approximately 35 minutes. If you think you will be unable to do this, please notify the technologist and they may be able to accommodate you.
How do I prepare?
- Do not eat for at least eight hours prior. Tanner recommends that you have nothing to eat for at least eight hours prior to your test (except water and your usual medications. However, do not take medication for diabetes without permission from your doctor).
- Drink water. You are encouraged to drink three to four glasses of water prior to arriving at Tanner for your procedure.
- Prepare a list that includes:
- Names of medications, vitamins and herbal supplements you are currently taking
- Brief medical history
- Treatments you have had (chemotherapy, radiation therapy, surgery)
- Any allergy to iodine
How long does it take?
You should plan for a total of two to three hours for the PET/CT procedure.