What is PET/CT?

PET/CT combines the functional information from a positron emission tomography (PET) exam with the anatomical information from a computed tomography (CT) exam into one single exam.

A PET scan detects changes in cellular function—how your cells are utilizing nutrients like sugar and oxygen. Since these functional changes take place before physical changes occur, PET can provide information that enables your physician to make an early diagnosis.

A CT scan uses a combination of X-rays and computers to give the radiologist a non-invasive way to see inside your body. One advantage of CT is its ability to rapidly acquire two-dimensional pictures of your anatomy. Using a computer, these 2-D images can be presented in 3-D for in-depth clinical evaluation.

The PET exam pinpoints metabolic activity in cells and the CT exam provides an anatomical reference. When these two scans are fused together, your physician can view metabolic changes in the proper anatomical context of your body.

Why is This Exam Important?
PET/CT exam results may have a major impact on your physician's diagnosis of a potential health problem—and, should a disease be detected, how a treatment plan is developed and managed.

A PET/CT exam not only helps your physician diagnose a problem, it also helps predict the likely outcome of various therapeutic alternatives, pinpoint the best approach to treatment, and monitor your progress. If you're not responding as well as expected, you can be switched to a more effective therapy immediately.

If your physician schedules you for a PET/CT, you may have the following questions.

What should I expect when I arrive?
When you arrive, we will take a review of your history and any past exams.

For the PET portion of the exam you'll receive a radiopharmaceutical injection. This is a radioactive tracer that must pass multiple quality control measures before it is used for any patient injection. PET radiopharmaceuticals lose their radioactivity very quickly (2 minutes to 2 hours) and only very small amounts are injected. In all cases, little or no radioactivity will remain in your body 10 minutes to 6 hours after injection.

For most studies, you'll have to wait for the radiopharmaceutical to distribute itself—typically 30 minutes to an hour. During this time, you will be asked to relax.

What will the scan be like?
You will lie on a comfortable padded table. The table will move slowly through the tube-shaped PET/CT scanner as it acquires the information needed to generate diagnostic images.

You will be asked to lie very still during the scan because movement can interfere with the results. For the CT scan, you will be asked to hold your breath for a few seconds to minimize body movements. During the scan, you might hear a humming noise but you will not feel anything unusual. You may feel the table move while images are being taken at certain locations on your body. The technologist will monitor you during the exam.

The specific details of your upcoming exam will be explained fully by the technologist or your physician.

How long will all this take?
The PET/CT scan should last between 30 and 45 minutes. The exam procedure can vary depending on what we are looking for and what we discover along the way. Plan to spend two to three hours with us.

What happens after the exam?
You may leave us as soon as the exam is complete. Unless you've received special instructions, you will be able to eat and drink immediately—drinking lots of fluids soon after the exam will help remove any of the radiopharmaceutical that may still be in your system.

In the meantime, we'll begin preparing the results for review by our diagnosticians, and then by your physician, who will tell you what we've learned.

How safe are PET/CT exams?
Be assured that PET/CT exams are safe and effective diagnostic procedures. The radiopharmaceuticals used in PET do not remain in your system long. However, it is suggested that you wait at least four hours before close contact with other people, particularly women who are pregnant or may be pregnant, infants and children. For example, please do not plan to travel with or dine out with women who are pregnant, infants, and children during that four-hour period.

Are there any instructions that I should know before the exam?

The following instructions are given to patients who are scheduled for a PET/CT exam.

Do not eat or drink anything except water for 6 hours before your exam because it could interfere with the results; don't even chew gum.

If you take medications, drink only enough plain water to swallow them.

If you've been advised not to take your medications on an empty stomach, eat nothing more than a few soda crackers within 6 hours of your exam.

If you are a diabetic, let us know ahead of time so we can work with your physician to determine the safest possible way for you to prepare for your exam.

If you feel feverish, please call this to our attention.

In addition, please let us know if you might be pregnant or are currently breast-feeding.

Should cancellation or rescheduling become necessary, we request a 24-hour notice since drugs are specially ordered for each patient.

Additional Information
If you have any questions regarding patient sedation due to claustrophobia, please call Cindy at 301-723-5536. If you have questions about your instructions prior to the procedure, please call Julie at 301-723-5536.

For appointments,
please call 301-723-1200 or Toll Free at 866-369-1122