What is a PET Scan?

Positron Emission Tomography, or PET, is one of the newest diagnostic imaging procedures. It produces three-dimensional images of the body which highlight certain abnormalities, particularly cancerous tissues.

A radiopharmaceutical containing glucose (sugar), which is the body’s fuel, is injected into the patient. After allowing sufficient time for the body to absorb the glucose, usually about 30 to 45 minutes, the patient is imaged by a large scanner. Abnormal tissues in the body will more actively absorb the labeled glucose, and will be specifically detected by the scanner. The information gathered is then fed into a powerful computer, which produces three-dimensional images.

PET scans can be used to diagnose disease and provide details regarding the stage of disease progression, thereby assisting physicians and their patients in determining treatment options.

Patient Experience

You should arrive at the center approximately 15 minutes before your appointment time for the usual screening procedures and paperwork. Before your exam, the PET technologist will obtain a brief medical history. Let the radiologist or technologist know if you have questions.

You will be asked to change into a patient gown. Your blood Glucose level will be measured. Then, an intravenous injection will be given to you while you are lying down. You will have a small amount of radioactivity in your body when you leave the facility.

After the injection, you will need to lie still and relaxed, without talking, for 30 to 45 minutes. This will allow time for any abnormal tissue to absorb the glucose radiopharmaceutical.

The technologist will then help you onto the examination table. The exam table will gently move into the opening of the scanner and will move through various automated positions over a period of about 45 minutes. You should feel nothing unusual during your exam. You will hear a whirring sound as the scanner operates, and you will be moved slightly after each section. It is important that you remain relaxed and still during the exam so the images do not blur. The technologist will speak to you through a two-way intercom system. You will be able to talk to the technologist if you need assistance at any time during the exam.

Exam Time

Although PET/CT exams are scheduled to minimize waiting time, unexpected delays may occur. Each examination is structured to the individual needs of the patient. On average, each procedure lasts approximately 2 to 2½ hours.


It is very important that the glucose levels in your body be carefully managed prior to the examination. For this reason, you will be asked to adhere to the following preparations:

  • • Nothing at all to eat for at least 6 hours prior to your appointment – not even chewing gum or breath mints. The nurse or technologist will check your blood sugar levels at the time of the appointment.

  • • Diabetic patients (insulin dependent) will require individual physician consultation. Your blood sugar must be below 200. Be sure to bring your regular insulin with you to your appointment.

  • • Limit your exercise and any physical exertion prior to the examination.

  • • Take all regular medications.

  • • Drink plenty of water to ensure hydration. You may be encouraged to drink more water after your arrival at the center.

  • • You will then be asked to empty your bladder just before the examination.

  • • If you have had previous diagnostic studies (MRI, CT scans, Ultrasound, X-ray, Bone scans) of the body part being evaluated, please bring those reports and films or request that they be sent to the center. These studies or reports are very helpful to the radiologist interpreting your PET/CT scan.

  • • Tell your doctor or the technologist if you are pregnant or breast feeding.


A specially trained radiologist will review and interpret the images and prepare a final report of findings to be sent to your referring physician who ordered the exam. Your physician can then explain to you what the findings mean.