Epilepsy and the PET Scan

What Is a PET Scan?

To diagnose the cause of epilepsy, a positron emission tomography (PET) scan may be used. A PET scan is a test used to give doctors and their patients more information about how the cells in your body are functioning.

This is done by injecting a small amount of radioactive material known as a tracer into a patient's vein, usually in the arm. The tracer sends out small, positively charged particles (positrons) that interact with negatively charged particles called electrons in your body. The PET scanner is able to detect the product of this interaction and uses it to make an image. This process allows a doctor to look at a body organ from every angle and detect potential problems.

Why Is a PET Scan Used in Epilepsy?

For patients with epilepsy, a PET scan is used to localize the part of the brain that is experiencing seizure activity.

However, doctors may request a PET scan for many different reasons. Aside from potential problems in the brain and spinal cord, the test can also be used to diagnose heart problems as well as certain kinds of cancer, including breast, brain, lung, colon, and prostate cancers and lymphoma.

How Do I Prepare for a PET Scan?

Before undergoing the PET procedure, be sure to tell your doctor of any medication -- prescription or non-prescription -- that you are taking, as well as any herbal drugs or supplements you may be using. It is also very important that you tell the doctor if you are pregnant or think you may be pregnant, since the PET scan can be harmful to an unborn child.

As the test is about to begin, you will be asked to take off clothing that is covering the area of the body to be tested. Depending on the area of your body being tested, you may be asked to undress completely and put on a hospital gown. You will also be asked to remove any dentures, jewelry, or metal objects during the scan, since these items may affect the reading.

How Is a PET Scan Conducted?

A PET scan usually lasts 45-60 minutes. You will be asked to lie down on a flat table that is next to a scanner computer and a camera. You will then be given the tracer through an IV. After that, the PET scanner, a doughnut-shaped instrument, will move in circles around you. As this is happening, the camera will take pictures of patterns left by the tracer chemical inside your body.

After the PET scan is finished, you will likely be asked to drink a lot of water or liquids during the next day in order to get rid of or flush the tracer chemical from your system.

Does the PET Scan Have Risks?

Because radiation is part of the test, there is always a small risk that cells or tissue may have received some damage following the PET procedure. However, the radiation levels from the tracer that is sent throughout the body are very low.

In addition, following the scan, patients may find that their arm is a little bit sore or that they experience redness where the IV was placed in the arm.

How Soon Will I Have My PET Scan Results?

PET scans are usually more extensive and detailed than similar tests that are available. Despite this, test results can usually be given within one to two days after the scan.