FDG Brain PET/CT (Metabolic Function)

Your physician or neurologist may recommend an FDG brain PET/CT when additional information about brain metabolism is needed to evaluate certain neurological conditions.

A FDG Brain PET/CT may be used to:

1. Evaluate Cognitive Changes: Help physicians evaluate patterns of brain metabolism in patients experiencing memory loss, changes in thinking or other cognitive symptoms.
2. Help Evaluate Dementia: Provide information about patterns of brain metabolism that may help physicians evaluate different types of dementia and neurodegenerative disease.
3. Evaluate Seizure Disorders: Help identify areas of abnormal brain metabolism that may be associated with seizures.
4. Provide Additional Diagnostic Information: Give physicians information about brain function that may complement other tests, including MRI, CT, neurological examinations and cognitive testing.

Your physician will determine whether an FDG brain PET/CT is appropriate based on your symptoms, medical history and other diagnostic information.

Before your scan, a small amount of FDG (fluorodeoxyglucose) is administered through an intravenous (IV) line. FDG is a glucose-like substance that allows the PET scan to show how different areas of the brain use glucose. The tracer travels through your bloodstream and is taken up by brain cells. The PET scanner detects signals from the tracer and creates images showing patterns of brain metabolism. The CT portion of the examination provides detailed anatomical images that help your radiologist identify the location of metabolic findings.

Step 1: Prepare at Home

Proper preparation helps ensure your PET/CT images are as accurate as possible.

For Non-Diabetic Patients

24 hours before your appointment:

• Do not participate in strenuous work or exercise.
• Do not receive a body massage.

6 hours before your appointment:

• Do not eat or drink anything except plain water. This includes no flavored water, seltzer water, coffee or tea.
• Do not chew gum or have candy or mints.
• You may take your regular daily medications.

For Diabetic Patients

24 hours before your appointment:

• Do not participate in strenuous work or exercise.
• Do not receive a body massage.
• Follow a low-carbohydrate diet.

8 hours before your appointment:

• Do not eat or drink anything except plain water. This includes no flavored water, seltzer water, coffee or tea.
• Do not chew gum or have candy or mints.
• Do not take diabetic medications. You may take other medications that are not for diabetes.

For All Patients:

• Stay well-hydrated by drinking water before your appointment.
• Do not wear clothing with metal, including zippers, clips or snaps.
• Do not wear jewelry.
• If you have high anxiety or claustrophobia, consult your physician about medication. Do not take it before arrival. Our team will advise you when to take it. If prescribed, you must bring a driver.
• Bring a photo ID and insurance cards.
• If you have prior PET, MRI or CT scans that were not performed at Fairfax Radiology or Inova, please bring copies of those images to your appointment.

Step 2: Check In

Please arrive at your scheduled appointment time.

Your appointment will take approximately 2 to 2½ hours, depending on the examination ordered by your physician.

Step 3: Radiotracer Administration

A technologist will place a small IV in your arm and administer FDG.

The tracer travels through your bloodstream and is taken up by brain cells. It allows the PET scanner to measure patterns of glucose metabolism throughout the brain.

Step 4: Resting Period

After receiving the tracer, you will rest comfortably in a quiet environment while the tracer circulates and is taken up by your brain cells.

It is important to remain relaxed and minimize unnecessary movement during this time.

Step 5: The Scan

You will lie comfortably on a padded table that slowly moves through the PET/CT scanner.

The scan is painless. You will need to remain still while the images are acquired.

The PET portion of the examination shows patterns of brain metabolism, while the CT portion provides anatomical information to help localize the findings.

Step 6: After Your Scan

Following the examination, you may eat and resume your normal activities and diet.

Drinking additional fluids is encouraged after your scan to help your body naturally eliminate the remaining radiotracer.

Yes. PET/CT scans use carefully controlled amounts of radiation for diagnostic imaging. The radioactive tracer naturally loses its radioactivity over time and is eliminated from the body.

Your physician will consider your individual medical needs when determining whether a PET/CT is appropriate for you.

The scan itself is painless. You may feel a brief pinch when the IV is placed. During the scan, you simply need to lie still while the images are acquired.

Plan to spend approximately 2 to 2½ hours at the imaging center. Your appointment includes registration, IV placement, administration of the tracer, the resting period and imaging.

No. For a standard FDG brain PET/CT, you should not eat or drink anything except plain water for the designated preparation period before your appointment.

Non-diabetic patients should fast for 6 hours before their appointment. Diabetic patients should fast for 8 hours and should not take diabetic medications during that period.

Please follow the specific preparation instructions provided by Fairfax Radiology.

Please let our scheduling team know if you have diabetes. Special preparation is required before your PET/CT, including following a low-carbohydrate diet and withholding diabetic medications during the designated period before your examination.

Brain metabolism refers to how brain cells use energy, primarily from glucose. Different areas of the brain normally have different levels of activity.

A FDG brain PET/CT scan can show patterns of glucose use that may provide your physician with additional information when evaluating certain neurological conditions.

An FDG brain PET/CT provides important information about brain metabolism, but it is one part of the diagnostic process. Your physician will interpret the results alongside your medical history, symptoms, neurological examination, cognitive testing and other diagnostic studies.

A specialized radiologist will review your PET/CT images and send a detailed report to your referring physician or neurologist. Your physician will discuss the findings with you and explain any recommended next steps.

Contact our Scheduling Department for an appointment:
Phone: 703.698.4441 Option 4
Fax: 703.698.5930
Or click here to make an appointment request

Please have your written physician order and your insurance card in hand when making your appointment.

For safety, children under 12 may not be left in the waiting room without a supervising adult. They may not accompany patients in the exam room. If supervision isn’t available, your appointment will be rescheduled.  Families of Obstetrical patients will be allowed in the room for a limited period of time, but only when an adult accompanies the minor children.