What is a brain PET scan?
Positron emission tomography (PET) is a highly sensitive technology that uses a radioactive substance to show the chemical and functional changes within the brain.
- Chemical and functional changes cannot be seen by other imaging methods, such as magnetic resonance imaging (MRI) or computed tomography (CT).
- A brain PET scan is very sensitive and can detect changes in the brain associated with seeing, hearing, and thinking.
- Images obtained from a PET scan help doctors diagnose a problem, choose the best treatment and/or see how well a treatment is working.
- PET scans can be particularly useful when they are digitally combined with the images generated from MRI or CT.
The radiopharmaceutical used is designed to go to the brain.
- A common type of radiopharmaceutical, fluorine-18 FDG (fluorodeoxyglucose), acts almost exactly like sugar.
- The brain consumes large amounts of glucose, so the radioactive sugar goes to the corresponding regions of the brain.
- Once the radiopharmaceutical is in the brain, the PET scanner obtains 3-D images of glucose in the brain.
When might a brain PET scan be needed?
A brain PET is used for various conditions, including:
- epilepsy - the brain PET can show which part of the brain is responsible for the seizures
- assessment of the function of a brain tumor
- assessment of brain damage due to trauma
- determine the effectiveness of surgery, radiation therapy and/or chemotherapy in patients with brain tumors
How should I prepare my child for a brain PET scan?
You will be given specific instructions when you make your child's appointment. It is very important that you follow all preparation instructions or the scan will be rescheduled. In general:
- Your child should not have any form of caffeine (including soda, tea and chocolate), nicotine or alcohol 12 hours prior to the scan.
- Your child should not have any solid food or fluids four hours prior to the scan.
- Your child is allowed to drink plain water, but no flavored water.
- You may give your child his or her normal medications on the morning of the scan.
- It is helpful to give your child a simple explanation as to why a brain PET scan is needed and assure him or her that you will be with him or her for the entire time.
- You may want to bring your child's favorite book, toy, or comfort object to use during waiting times.
- If MR and/or CT scans have been done at a facility other than Children's, please bring those images with you. The nuclear medicine physician will compare the MR and CT scan to the brain PET scan.
- If your child's doctor has given you a requisition for the exam, please bring it with you. If we have to call the doctor's office to get the requisition after you have arrived for the appointment, this will cause a delay in performing the scan.
- If your child is scheduled for sedation or if you think sedation is necessary (to hold still) and a nuclear medicine staff member has not contacted you, please call us at 617-355-7010 for specific instructions.
You should expect your visit to last from one and one half to two hours.
What should I expect when I bring my child to the hospital for a brain PET scan?
When you arrive, please go to the Nuclear Medicine check-in desk on the second floor of the main hospital. A clinical intake coordinator will check in your child and verify his registration information.
What happens during a brain PET scan?
Obtaining a brain PET scan involves three steps: injection of the radiopharmaceutical, a waiting period and scanning by the PET machine.
Injection of the radiopharmaceutical:
- You will be greeted by one of our nuclear medicine technologists who will explain the scan in detail to you and your child.
- A tiny amount of the radiopharmaceutical will be injected into one of your child's veins by a small needle.
- Once the radiopharmaceutical reaches the brain, it will transmit signals (gamma rays) that can be detected from outside the body by the PET scanner.
The waiting period:
- After the injection, your child must wait for 30 minutes.
- During this time, while the radiopharmaceutical is circulating within the body, it is extremely important for your child to be very quiet - no talking, reading or sleeping. These activities can alter the radiopharmaceutical distribution in the brain and affect the image.
- The lights in the room will be dim to help your child relax.
The PET scan:
- You and your child will be taken to the PET suite. You are welcome to sit in the room with your child during imaging.
- Your child will be asked to lie on the imaging table.
- The table will slide into the scanner.
- Your child must remain still while the images are taken.
- The technologist will be watching the procedure through the window and by TV monitor.
- While your child lies within the scanner, a computer will create images of the body.
Your child will be in the scanner from 15 to 30 minutes.
A brain PET scan picture:
Will my child feel anything during a brain PET scan?
Your child may experience some discomfort associated with the insertion of the intravenous needle. The needle used for the procedure is small. Once the radiopharmaceutical is injected, the needle is withdrawn and a gauze bandage with adhesive tape is placed over the site of the injection. The area where the injection was given may be a little sore.
The PET scanner does not touch your child, nor will he or she feel anything from the scanner.
Is a brain PET scan safe?
We are committed to ensuring that your child receives the smallest radiation dose needed to obtain the desired result.
- Nuclear medicine has been used on babies and children for more than 40 years with no known adverse effects from the low doses we use.
- The radiopharmaceutical contains a very tiny amount of radioactive molecules, but we believe that the benefit to your child's health outweighs potential radiation risk.
- The camera used to obtain the images does not produce any radiation.
What happens after the brain PET scan?
Once the brain PET scan is complete, the images will be evaluated for quality. If the scan is adequate, your child will be free to leave and resume normal activity.
One of the Children's nuclear medicine physicians will review your child's images and create a report of the findings and diagnosis.
How do I learn the results of the brain PET scan?
The nuclear medicine physician will provide a report to the doctor who ordered your child's brain PET scan. Your child's doctor will then discuss the results with you.