PET Scan

Introduction

A PET (positron emission tomography) scan is a test used to detect changes in the tissues and organs of your body. 

X-rays, CT scans and MRI show the shape and structure of your body’s organs and tissues. A PET scan shows how they work. A PET scan can often find changes in your body’s tissues before changes can be seen in their structure.

How Does a PET Scan Work?

A PET scan uses small amounts of radioactivity, called a radionuclide, to take detailed pictures of different areas inside your body. A small dose of this radionuclide is combined with a sugar and injected into a vein in your hand or arm. The radionuclide gives off positively charged energy particles, or positrons. The PET scanner rotates around the body to detect these positrons at many different angles.

How Should I Prepare for a PET Scan?

Follow these simple steps in preparing for your test

• You should not eat or drink for four to six hours before your appointment.
• If you need to take medications, you may take them with a small amount of water.
• If you are diabetic, contact your physician for specific instructions. You may need to follow special guidelines, such as taking a reduced dose of insulin on the morning of the scan.
• If your brain is being scanned, you will need to wait quietly, usually in a dimly lit room. You will need to avoid any mental stimulation such as reading or talking.

If other areas of the body are being scanned, you will be able to read, listen to music, watch TV, etc.

What Will the Procedure Feel Like?

You may spend two to three hours at the imaging center. The actual scanning time is anywhere from 15-20 minutes. The time can vary depending on the number of areas being scanned that day.

This is what you can expect during a PET Scan:

• When you arrive at the imaging center, a soft, flexible tube or needle will be inserted into a one of your veins. The radionuclide will be given to you through this tube.
• You may need to wait about 30-60 minutes for the radionuclide to reach the organs that you are having scanned.
• You may be asked not to speak during the procedure in order to prevent the radionuclide from going to your tongue or vocal cords.
• You will be placed on a flat table that moves through a donut shaped opening on the PET scan machine. The scan makes no noise.
• If you become uncomfortable lying still for a long time or if you are uncomfortable with close spaces, you may request a sedative to help you with the PET scan.
• During the scan, you will need to lie very still because any movement could interfere with the test results. The table moves and glides you through the machine, so you do not need to move.
• If you were not sedated, you may leave as soon as the scan is complete.
• Unless you receive special instructions, you may eat and drink immediately and go back to your usual activities and diet.

Risks

No side effects are associated with the radionuclide tracer. The tracer is eliminated rapidly from your body, making it safer for you to be near others during and immediately after a PET scan.