Positron Emission Tomography (PET)

What is an PET Exam?

A PET (Positron Emission Tomography) scan,  is a diagnostic examination that involves the acquisition of physiologic images based on the detection of radiation from the emission of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient. The subsequent images of the human body developed with this technique are used to evaluate a variety of diseases. Before the examination begins, a radioactive substance is produced in a machine called a cyclotron and attached, or tagged, to a natural body compound, most commonly glucose. Once this substance is administered to the patient, the radioactive sugar localizes in the appropriate areas of the body and is detected by the PET scanner.

How do I prepare?

Please consult the Patient Preparations chart to determine the pre-test preparations for your specific diagnostic imaging exam.   You will receive a letter from the testing site/referring physician which will outline the preparations specific to your test.

Dress casually and in loose clothing when you come for a PET procedure, as more than likely you will have to change into a gown. Dressing in a casual manner allows ease in changing. You may not have to remove all of your clothing, but the technologist will let you know exactly which items need to be removed for the procedure.   You may also be asked to remove any jewellery such as watches, necklaces, earrings and body piercings which would interfere with acquiring the image. 

What is involved?

A specially trained Nuclear Medicine Technologist Technologist will take you into a special injection room, where a radioactive substance is administered as an intravenous injection (like a blood test). Blood sugar levels are monitored prior to the injection. If the blood sugar level is too high, it will interfere with the uptake of the injected material and impact the results. You may have to have the procedure rescheduled if the blood sugar is high.

It will then take approximately 30 to 90 minutes for the substance to travel through your body and accumulate in the tissue under study. During this time, you will be asked to rest quietly and avoid significant movement or talking, which may alter the localization of the administered substance. After that time, scanning begins. The machine looks like a large doughnut. There are no loud noises or radiation coming from the machine. Patients who are claustrophobic may feel some anxiety while positioned in the PET machine. The scan usually takes 20-35 minutes. The radioactive material has a very short effective shelf life (half-life) and therefore timing of the study is critical. Patients must be on time for their test with the proper preparation done.

Usually, there are no restrictions on daily routine after the test, although you should drink plenty of fluids to flush the radioactive substance from your body. You will not feel anything related to the radioactivity of the substance in your body.

How long will it take?

Patients should allow 2 - 2.5 hours for the procedure. There are no side effects and there are no restrictions after the test is over. Patients are able to eat and drink normally after the test. Patients are able to drive after the test.

How do I get my results?

Patients undergo PET because their referring physician has recommended it. A radiologist who has specialized training in PET will interpret the images and forward a report to your referring physician.  The value of a PET scan is enhanced when it is part of a larger diagnostic work-up. This often entails comparison of the PET scan with other imaging studies, such as CT or MRI.

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