PET/CT is the fusion of PET and CT scanning into one imaging system. 

The PET scans show metabolic changes occurring at the cellular level in an organ or tissue. This is important because disease often begins at the cellular level. CT scans and MRIs don't detect problems at the cellular level.

Unlike other scans, a brain PET scan allows doctors a view of not only the structure of the brain, but how it’s functioning as well.

PET scans are most commonly used to detect:

  • brain tumors
  • brain disorders
  • issues with the central nervous system
  • memory disorders
  • seizure disorders

This improves the ability to localize and characterize a disease process or lesion more accurate.

When a PET scan is combined with a CT, it results in what’s called image fusion. A computer combines the images from the two scans to create a three-dimensional image, which provides more information and allows for a more precise diagnosis.

How to prepare for a brain PET scan

Your doctor will provide you with complete instructions to help you prepare for your brain PET scan.

Alert your doctor to any medications you may be taking, whether they’re prescription, over the counter, or even nutritional supplements.

You may be instructed not to eat anything for up to eight hours before your procedure. You will be able to drink water.

Tell your doctor if you’re pregnant or believe you could be pregnant. The test might be unsafe for your fetus.

You should also tell your doctor about any medical conditions you may have. For example, people with diabetes will likely be given special instructions for the test. Fasting beforehand could negatively affect their blood sugar levels.

Immediately before the test, you may be asked to change into a hospital gown and remove all of your jewelry.

How a brain PET scan is performed

You’ll be seated in a chair in the procedure room.

A technician will insert an intravenous catheter (IV) into your arm. A special dye with radioactive tracers will be injected into your veins through this IV.

You will wait about an hour while your body absorbs the tracers as blood flows through the brain.

When it's timefor the scan, you'll lie on a narrow table attached to the PET machine, which looks like a giant toilet paper roll. The table glides slowly and smoothly into the machine so the scan can be completed.

You will have to lie still during the scans. The technician will tell you when you need to remain motionless.

The scans record brain activity as it’s happening. These can be recorded as video or as still images. The tracers are concentrated in areas of increased blood flow.

When the desired images are stored in the computer, the test is complete and you'll be removed from the machine. 

Following up after a brain PET scan

Drink plenty of fluids after the test to help flush the tracers out of your system. Generally all tracers are out of your body after two days.

Other than that, you’re free to go about your life unless your doctor gives you other instructions.

Meanwhile, a specialist trained in reading PET scans will interpret the images and share the information with your doctor.

Your doctor will then go over the results at a follow-up appointment.