What is a PET scan?

PET scans are used most often to detect cancer and to examine the effects of cancer therapy. These scans can be performed on the whole body. PET scans of the brain are used to evaluate patients who have memory disorders of an undetermined cause, suspected or proven brain tumors, or seizure disorders that are not responsive to medical therapy and may be helped by surgery.

PET is usually done on an outpatient basis. Your doctor will give you detailed instructions on how to prepare for your examination. You should wear comfortable, loose-fitting clothes. You should not eat for four hours before the scan. You will be encouraged to drink water. Your doctor will instruct you regarding the use of medications before the test.

Note: Diabetic patients should ask for any specific diet guidelines to control glucose levels during the day of the test from the department. Do not take your diabetic medication before the procedure.

Please bring your physician's orders, insurance card and picture I.D. with you on the day of the exam. Family members are invited to stay in our waiting area for the duration of your procedure.

A radioactive substance is attached, or tagged, to a natural body compound, most commonly glucose. Once this substance is administered to the patient, the radioactivity localizes in the appropriate areas of the body and is detected by the PET scanner.

Different colors or degrees of brightness on a PET image represent different levels of tissue or organ function.

A technologist will take you into a special injection room. In this room, a blood glucose will be drawn and a radioactive substance will be administered through the vein. The wait time pre-scan is approximately 30 to 90 minutes. During this time, you will be asked to rest quietly and avoid significant movement or talking. After that time scanning will begin. This may take 30 to 45 minutes.

Usually, there are no restrictions after the test, although you should drink plenty of fluids to flush the radioactive substance from your body.

The administration of the radioactive substance will feel like a slight pinprick when given by intravenous injection; you will not feel anything related to the radioactivity of the substance in your body.

You will then be made as comfortable as possible before you are positioned in the PET scanner for the test. You will be asked to remain still for the duration of the examination.

Patients who are claustrophobic may feel some anxiety while positioned in the scanner. While you will be alone in the exam room, the technologist will be able to see you and communicate with you throughout the exam. Some patients find it uncomfortable to hold one position for more than a few minutes.

If you have difficulty lying down or remaining still because of pain, you may wish to speak to your physician before the CT scan about the possible benefits of pain medication for the exam. It is important to remain as still as possible during the PET exam because any movement will affect the quality of the image produced.

After the procedure is complete, a nuclear medicine physician will study the pictures along with your medical history to make an assessment of what the photos show. They will then dictate a report that will be forwarded to your physician within three business days. If the results are needed sooner, your doctor may contact the nuclear medicine physician on the day of the exam.

Yes, a PET scan and CT scan can be done in the same appointment. Your physician will determine if a CT scan is to be combined with a PET scan. A CT can be done as a separate study in the Radiology Department, but if there is more information required and a PET study is the preferred approach, then a combined procedure will be ordered. A combined study will take approximately two hours.

A PET scan usually takes about 30 minutes, but it can take up to 60 minutes for your body to absorb the injected radiotracer. During this time, you'll need to sit quietly and limit your movements. You can expect to be in the PET imaging department for between two and three hours.