What is a PET/CT scan?

PET/CT is a type of nuclear medicine imaging that is highly advanced. PET/CT combines two different types of imaging into one procedure. PET and CT together produce a more accurate picture of what is happening in the body than either PET or CT alone, providing more accurate diagnoses. PET/CT is a very good tool for detecting the severity of many types of cancers as well as detecting many other abnormalities within the body.

What is PET?

A PET scan measures important body functions, such as blood flow, oxygen use, and sugar (glucose) metabolism, to help doctors evaluate how well organs and tissues are functioning. These imaging scans use radioactive materials called radiopharmaceuticals or radiotracers. Depending on the type of exam, the radiotracer is either injected into the body, swallowed or inhaled as a gas.

What is CT?

“CT” is short for computed tomography. CT uses x-rays and a computer to make an image of sections of your body. A CT scan shows your body’s organs, bones, and tissues in greater detail than regular x-rays do. For your CT scan, you may receive a contrast enhancing agent by intravenous line (IV), which helps produce an even clearer image. CT exposes you to a small amount of radiation.

What does PET/CT do?

A PET image is color coded — different colors show various levels of cell activity. A CT scan shows the exact locations of the body’s organs and also can show abnormal growths. When a CT scan is laid over a PET scan, doctors can pinpoint the exact location of abnormal cell activity. They can also see the level and extent of that activity. Even when an abnormal growth is not yet visible on a CT scan, the PET scan can show the abnormal cell activity.

What are some common uses of the procedure?

Detect cancer.

Determine whether a cancer has spread in the body.

Determine if a cancer has returned after treatment.

Determine blood flow to the heart muscle.

Determine the effects of a heart attack on areas of the heart.

Evaluate brain abnormalities, such as tumors, memory disorders, seizures and other central nervous system disorders.

Map normal human brain and heart function.

How do I prepare for my PET/CT exam?

This section gives you general guidelines to prepare for your exam. Your doctor, nurse, or testing center will give you more detailed instructions.

-You will receive specific instructions based on the type of PET scan you are undergoing.

-Wear loose-fitting, comfortable clothes to the test.

-You should inform your physician and the technologist performing your exam of any medications you are taking, including vitamins and herbal supplements. You should also inform them if you have any allergies, asthma and about recent illnesses or other medical conditions.

-If you are pregnant or think you might be, or if you are breast-feeding, tell your doctor or technologist before the exam.

-If you are a large person or have a fear of enclosed spaces, tell your doctor before the day of your PET/CT exam. The doctor can prescribe medicine to help you relax.

-Do not schedule any other test that uses radioactive material for the same day as your PET/CT exam.

-Plan to be at the testing center for 2 to 2 1/2 hours on the day of your PET/CT exam. It is very important to arrive on time at the testing center.

-If you cannot come to the testing center at your scheduled time, please call 48 hours in advance to reschedule your test.

What happens before the exam?

You will need to remove all metal objects that could interfere with the scan. If necessary, an IV will be inserted in your arm. You may receive the radiotracer, a drug that emits radioactivity, via an IV, by swallowing or inhaling as a gas. Typically, it will take approximately 60 minutes for the radiotracer to travel through your body and to be absorbed by the organ or tissue being studied. You will be asked to rest quietly, avoiding movement and talking. You may be asked to drink some contrast material that will localize in the intestines and help the radiologist interpreting the study.

What happens during the exam?

You may be asked to empty your bladder, and then you will go to the scanning room. The PET/CT scanner is a machine that does PET and CT scanning in the same procedure. It has a large, deep ring — like a donut standing on its side. The CT exam will be done first, followed by the PET scan.

The technologist will help you onto the table. You must be able to lie very still on the table for the entire test which takes approximately 30 minutes.

Next you will receive the enhancing agent through your IV. A brief sensation may move up your arm. You also may get a warm, flushed feeling; a taste of salt or metal in your mouth; or nausea for a few minutes. This is normal, but you should tell the technologist about these or other reactions. You may also have nausea, shortness of breath, itching, or sneezing. If any of these occur, tell the technologist right away.

The technologist will go into a room behind a glass window. The technologist can see you at all times during scanning and may give you added instructions. You’ll be able to talk to the technologist through an intercom during the scan. You should lie as quietly as possible. The scan is painless; you should not feel anything.

How do I get my results?

Your final report will be sent to your referring physician within 48 hours of the test. Your referring physician will discuss the results with you during your follow-up appointment.