PET/CT FREQUENTLY ASKED QUESTIONS

Excel Diagnostics & Nuclear Oncology Center

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PET/CT

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PET/CT Positron Emission Tomography and Computerized Tomography

Doctors, especially cancer surgeons, were often frustrated in trying to match PET images with CT images to determine the precise location of a tumor in relation to an organ or the spinal column. They had little choice other than to “eyeball” the two separate images and make an educated guess as to the tumor’s exact location – until 1992, when engineer Ron Nutt and physicist David Townsend came up with the idea of combining a PET and CT into one machine. After working on their combined PET and CT concept for three years, Nutt and Townsend received a grant from the National Cancer Institute. This enabled the completion of a prototype machine, which was installed at the University of Pittsburgh medical center in 1998. The pair designed the machine to be more patient-friendly by making the diameter of the PET/CT tunnel 28 inches, far more spacious than the typical MRI tunnels. Time Magazine honored PET/CT as the “Medical Science Invention of the Year” in 2000, noting that the PET/CT scanner has “provided medicine with a powerful new diagnostic tool.”1

The first PET/CT scanner was introduced in 2000. This hybrid marries two technologies, simultaneously showing both anatomical structure and cellular function, providing complete information on the location and metabolism of cancer. These combined PET/CT systems greatly facilitated interpretation of the digital images.

^{1 Jaroff, L. Time Magazine (2000, December 4).}

PET/CT: Frequently Asked Questions

What to Expect
Procedure
How Long Will the Scan Take?
Diabetics
After My PET Scan
Results of My PET Scan
Is PET Safe?
What is a radiopharmaceutical?
What is FDG?
What happens after my scan?
Are there potential side effects to a PET scan?
When will I get my results?
How often should I have a PET scan?
Can I see my results?
Are there alternatives to PET?
What should I do if my physician does not know about PET?
Why is PET not well known? Why have I never heard of PET before?
How many PET studies are performed per year?
How does a PET scan differ from CT or MRI scans?
Is a PET scan painless?
How much does a PET scan cost?

What to Expect
Some hints to prepare you for your scan:
Dress comfortably and warmly. Scanner rooms can sometimes be cool.
Avoid eating anything for at least four-six hours before your scan (this includes sugar-free gum, mints, candy and beverages other than water).
No strenuous exercise the day of your exam (example: working out, jogging, etc.). Please bring a copy of your most recent CT, X-Ray, or MRI films with you on the day of your PET scan.

Procedure
Be prepared to lie still for 15-75 minutes while the scan is performed.
A PET scan is completely painless and has no side effects. After fasting for 4-6 hours, you will receive an injection of a trace amount of radioactive glucose, which is distributed throughout the body.
About 30-70 minutes after the injection, you will empty your bladder, then lie down on a scanner bed. Images will be taken of your body as you lie still on the scanner bed.

How Long Will the Scan Take?
A scan takes approximately 15-90 minutes, depending on the type of scan you are having (i.e., whole body, brain, etc.) and the type of scanner being used. The results are then interpreted by a trained nuclear medicine physician or radiologist and sent to your referring physician.

Diabetics
If you are diabetic, eat and take your insulin or oral medication as directed by your physician. Generally, your blood sugar level should be 100-200 mg/dL before your PET scan. Test your blood sugar level before the PET scan. Make sure that the PET center staff knows that you are diabetic..

After My PET Scan
When the PET scan is done, make sure to drink plenty of water or other fluids throughout the day.

Results of My PET Scan
Your PET scan results will be reported to your referring physician within 1-2 business days. Please contact your physician to discuss your PET scan results.

Is PET Safe?
The risks associated with a PET scan are very minimal. The quantity of radiation is low and the FDG degrades quickly so that no detectable radioactivity is present after several hours. In addition to the radioactive decomposition, the remaining FDG is eliminated from the body through urine. Family members are not at risk for exposure since greater than 90% of the radioactivity has left the body or decomposed before the patient has left the center.

What is a Radiopharmaceutical?
A radiopharmaceutical is a radioactive drug. The most commonly used PET radiopharmaceutical is FDG, which is a radioactive form of glucose (sugar). Radiopharmaceuticals are produced by physicists and chemists.

What is FDG?
2-Deoxy-2-[18F]fluoro-D-Glucose, or FDG, is a type glucose (sugar) and is the most common radiopharmaceutical used in PET. To begin the PET procedure, a small amount of glucose is injected into your bloodstream. There is no danger to you from this injection. Glucose is a common substance that every cell in your body needs in order to function. Diabetic patients do not need to worry; it would take 1,000,000 doses of FDG to equal the glucose in 1 teaspoon of sugar.
FDG has a half-life of approximately 110 minutes, so it is quickly expelled from your body. FDG must pass multiple quality control measures before it is used for any patient injection.

What happens after my scan?
After your scan, you will get up from the scanner bed and check out with the receptionist. You will be notified when your results will be available to your physician.

FDG has a half-life of approximately 110 minutes, so it is quickly expelled from your body. FDG must pass multiple quality control measures before it is used for any patient injection.

Are there potential side effects to a PET scan?
No, there are no side effects to having a PET scan performed.

When will I get my results?
After the radioactive tracer is processed by the organ being studied and the scanner records the information, the images are interpreted by a trained radiologist. Your PET scan results will be sent to your physician generally within 24-48 hours of your PET scan.

How often should I have a PET scan?
If you are under a physician’s care, you should follow your physician’s recommendations for the frequency of having a PET scan.

Can I see my results?
Yes, your physician will have the PET scan results usually within 1-2 business days of your PET scan, and you may request a review of the PET scan results with your physician.

Are there alternatives to PET?
Yes and no. There are examinations that can be performed. However, there is no other metabolic (biological) scanning technique other than PET at this time. CT and MRI, for example, both examine the anatomical (physical) structure. Therefore, they can be useful in determining the size and location of a tumor; however, neither of them can determine whether a tumor is still active. No other imaging tool exists that scans for brain disorders.

What should I do if my physician does not know about PET?
If your physician does not know about PET, you can direct him/her to http://www.petscaninfo.com/PhysicianPortal for additional information. You can also enter your physician’s name and address into the form on the Patient Portal to have additional information mailed to him/her by clicking here. You may also wish to seek a second opinion.

Why is PET not well known? Why have I never heard of PET before?
While PET has been around for years, it has only been in the last few years that PET has moved from the research realm to the diagnostic/clinical sphere.

How many PET studies are performed per year?
Approximately 900,000 PET scans were performed in 2004. The number of PET scans are increasing dramatically, now that PET is no longer only for research.
It is estimated that by 2010, in excess of 2,000,000 PET scans will be performed.

How does a PET scan differ from CT or MRI scans?
CT and MRI scans are anatomic imaging modalities, which means they look at the size and shape of organs and body structures. A PET scan is a metabolic imaging modality, which means it looks at function. The information collected from a PET scan is different from any other test that is available.

Is a PET scan painless?
The only pain involved is the needle prick when you receive the radiopharmaceutical injection which does not differ from any other type of injection.

How much does a PET scan cost?
A PET scan generally costs anywhere from $3,000 to $6,000.

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