PET Scan

What is a PET Scan?

PET stands for positron emission tomography. It is a scanner-type imaging test with cameras that detect binding sites within the body for a radioactive tracer that was intravenously injected. The tracer contains sugar that likely binds to tumor or inflammatory cells. Indeed, cancer cells consume more glucose than normal cells.

What is the purpose of PET scan?

The PET scan is a complementary examination to X-rays, computer tomography (CT) scans, and non-magnetic resonance (NMR) imaging, but it does not replace them. On the contrary, it enables us to visualize tumors that have gone unnoticed upon the other examinations, to follow-up the evolution of cancer during treatment, and to detect possible relapses.


The examination lasts about 30 minutes. The preparation for this takes a minimum of 1h30.

How to prepare for it?

In order for the examination to go well, the stomach must be empty. The patient should not eat, drink, or smoke for 6 hours prior to the investigation. If the examination is scheduled to be in the morning, the patient should neither eat nor drink after midnight. If the examination is scheduled to be in the afternoon, a light breakfast before 7am is allowed, after which the patient must fast. However, the patient is still allowed to drink water or black coffee and to take any medication (unless otherwise specified by the doctor).

Medications can be taken as usual.

For diabetic patients, insulin should be taken as usual. A light breakfast and subcutaneous injection of insulin are possible, provided there is a minimum 4-hour delay prior to the examination.


To perform the examination, an infusion is placed into a vein of the elbow through which the tracer is to be administered. Your blood sugar level will be systematically checked in order to ensure the quality of the examination. You will then have to sit quietly in the injection chair, waiting for the radio tracer to be diffused, and this, for at least 1.5 hours. During this period, you will be provided with water to drink to ensure good hydration and good elimination of the uncaptured tracer.

During the examination, you will be asked to lie on your back with your head in a rigid support. Strict immobility is essential for the proper conduct of this examination.

What happens after the procedure?

You will be able to leave the department after it has been checked that the images taken are of good quality. The report will be sent as soon as possible to the prescribing physician, who will inform the patient with regard to the results and conclusions.

Risks and discomforts/Complications/Disadvantages

The product administered (the fluorine-labeled sugar, called FDG) is weakly radioactive and does not represent a health hazard. This tracer has been used for more than 15 years in Belgium and has been administered to several tens of thousands of patients without any recorded unwanted effects. There are no allergic reactions to fear with this product. Although the radioactive lifetime of the product is extremely short, it is recommended to avoid being around pregnant women or young children on the day of the examination. The patient will be asked to drink plenty of water to facilitate the urinary elimination of the uncaptured tracer.

The return home

The radioactive sugar injected for the examination is weakly radioactive and disappears rapidly from the body. It is eliminated mainly through urine: It is therefore advisable to drink plenty of fluids in order to eliminate it more quickly.

When leaving the department, the radiation emitted is very low. This is why no precautionary measures are usually required. Nevertheless, it is recommended to avoid prolonged contact with pregnant women and young children for 4 hours following the examination.


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