Positron Emission Tomography CT (PET-CT)

PET-CT effectively combines two modalities. First, the CT scan uses X-rays to produce a detailed “map” of the body. For that reason, the machine looks much like an ordinary CT machine, with a narrow table on which the patient is positioned, and a bore in the middle through which this table can move.

Immediately after the CT imaging is complete, the PET scan does the imaging of cell activity and the abnormal activity’s precise location in the body.

To enable the imaging, a small amount of a radioactive substance is injected into the body and usually left for about 60 to 90 minutes to be absorbed by the cells. The radiation that is emitted by the radiopharmaceutical during cell activity, is then used to produce a functional image of normal and abnormal tissue.

The process involves a team of clinicians that includes specialist nuclear physicians, radiologists, nuclear medicine radiographers and a radiopharmacist.

It is important to note that a PET-CT scan has a very specific place in medicine and that it doesn’t replace or outperform other modalities.

Since the scan investigates metabolic function in the body, it is very important that you adhere to instructions on factors that might influence the outcome of the study, such as diet, fasting, insulin and other medication, and physical activity.

Instructions also differ depending on the type of radiopharmaceutical that will be used for your specific study, while there may be special instructions if you are a diabetic.

To form a general idea of the preparations you might need to undergo, click here. It is critical, however, that you share your full medical history with the specialist who provides your treatment, and follow the exact instructions that your doctor supplies prior to the scan.

If you think you may need a sedative or anti-anxiety medication during the scan, organise someone to take you home when it is done.

You will be asked to fill out a questionnaire about your current state of health, but also:

• Tell the radiographer if there is any possibility that you might be pregnant, if you are breastfeeding or if you have any allergies.
• Tell the radiographer if you suffer from claustrophobia.
• Bring all available images from previous scans.
• Bring a list of the medication that you normally take.

After completing the necessary paperwork, your weight and other health readings will be taken. A glucose test may be performed to make sure your blood sugar levels are within safe parameters for the test.

The radiopharmaceutical will be administered and you will be asked to wait in a special waiting room for patients only. Note that you could wait for up to two hours, depending on the specific type of pharmaceutical you received, and that you will not be allowed to leave the waiting room.

The radiographer will check that you’re appropriately dressed and you may have to wear a gown.

You will be asked to empty your bladder and then be positioned on the PET-CT machine. As a rule, the scan would need to be done from the lower part of the head down to the thighs, but in some instances a whole-body scan from head to toe would be necessary.

The session usually takes about 15 to 25 minutes and you will be required to lie very still to enable an optimal image.

Overall, you might spend two to two and a half hours at the centre.

You’ll be allowed to eat straight after your scan, so feel free to bring along something to eat or to drink.

Staff will not discuss the scan with you and the complex process of reporting on the scan may take several hours. The report should reach your own referring doctor the next day.

You should be able to carry on with normal daily activities and it’s advisable to drink lots of water after the scan.

The radioactive substance loses effectiveness very quickly and will also pass through the body within a few hours.

• Wear comfortable clothes, preferably without zips or metal attachments.
• Keep yourself warm, as this improves the quality of the image.
• Drink plenty of unflavoured water before and after the scan.