This imaging test helps doctors see both the structure and function of cells and tissues in the body to look for signs of disease, mostly cancer. By combining two scans in one – a positron emission tomography (PET) scan and a computed tomography (CT) scan – the PET/CT test provides very useful and detailed information.

For this test, a safe radioactive substance called a "tracer" is injected into your body to look for disease. This tracer then collects in specific areas of your body based on changes in your cells and tissues.

  • The PET scanner finds the tracer and gathers images of your body's organs and tissues
  • The CT scanner provides an internal map of your body, showing areas that "light up" where the tracer accumulates

When Are PET/CT Scans Used?

PET/CT scans are used to assess a variety of conditions, including:

  • Cancer
  • Neurological disorders (for example, epilepsy, Alzheimer's disease)
  • Heart disease

Your doctor can use these images to:

  • Diagnose - or rule out - disease
  • Determine the extent of the disease or how much it has spread
  • Track its progression (or for cancer, to see if it has returned)
  • Guide treatments and see how well therapy is working

Preparing for a PET/CT Scan

Your doctor will provide information about how to best prepare for your specific PET/CT scan. In general, you should:

  • Arrive on time.

    • Sufficient time is needed for the tracer to be absorbed in your body before the test can begin.
  • Bring a list of current medications.
  • Wear comfortable, loose-fitting clothing; you may be given a gown to wear during the exam.
  • Remove jewelry, hair clips, eyeglasses or other metal objects, which can affect the images.
  • Follow any instructions that were given to you. For example, for many PET/CT tests, you may be asked to avoid:

    • Exercising or strenuous activity for 24 hours before your test. Too much exercise before the exam can pull the tracer to active muscle tissue which can impact the quality of the exam.

    • Eating or drinking anything other than water for four hours prior to the scan.

  • Tell your doctor or technologist if there's any chance you could be pregnant.

Since some PET/CT scans require a mild sedative, check to see whether this applies to your test and if someone will need to drive you home after the test. Be sure to talk with your doctor about any concerns you might have before your test date.

What to Expect During and After a PET/CT Scan

Here's what you can expect before the test:

  • A Technologist will greet you and take you to an exam room.
  • He/she will carefully insert an intravenous line into a vein in your arm or hand and inject the tracer.
  • You'll need to wait while the tracer is absorbed by the part of the body being examined. During this period (usually 45 minutes to an hour), you may be asked to rest and avoid talking or moving around.

During the test:

  • When it's time to begin your scan, you'll lie on a narrow table.
  • The table, which is on tracks, will slowly move you into the PET/CT scanner, which is shaped like a small tunnel.
  • Try to stay as still as possible to avoid blurring the images.
  • Even though you'll be alone in the exam room, your technologist will be close by and can monitor and see you through a window. He/she will check in with you over a speaker at times during the test.

After the test:

  • You will need someone to drive you home if you were given medication to help you relax.
  • Contact your doctor with any questions or concerns.

A radiologist (a doctor who uses medical imaging techniques to find or treat diseases or injuries) will look at the images and send a report to the doctor who ordered the exam. Your doctor will help explain what the results mean for you.

For More Information

For more information or if you have specific questions, please contact the care provider who ordered your PET/CT scan.

If you need to schedule your PET/CT test, please call 1-704-512-2060.

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