What is PET-CT Scan?

Positron Emission Tomography (PET) is an imaging procedure showing the chemical function of an organ or tissue rather than its structure. The PET scanner detects the activity in your organs and tells whether it is normal or not.

A PET-CT scanner is a very specialized medical imaging device which combines in a single gantry system both a Positron Emission Tomography (PET) and an x-ray Computed Tomography (CT). The combination of the two scans has been proven to be extremely sensitive for detecting the early stages of disease, and can detect abnormalities even in the absence of structural change. Small tumours may be found even if they are undetectable by other imaging procedures or CT alone, which can be a major impact on choosing the best treatment for patients.


What are some common uses of the procedure?

PET-CT scans are performed:
  • To detect cancer cells
  • To determine whether cancer cells have spread in the body
  • To assess the effectiveness of a treatment plan, such as radiotherapy or chemotherapy
  • To detect any recurrent tumours
After the PET-CT scan
  • If you had an intravenous line or catheter inserted for the procedure, it will usually be removed unless you are scheduled for other procedure on the same day.
  • You may be asked to wait in the rest room for approximately 20-30 minutes until the technologist and physician checks the images in case additional images are needed. Occasionally, some delayed scan is needed for better visualization of certain areas or structures.
  • You will be expecting to be in the PET-CT Centre for 2-3 hours.
  • You may resume your normal diet and activities after your scan.
  • Radiotracer that had been injected in your body will lose its radioactivity over time. It may be pass out of your body through your urine and stool during the first few hours following the scan. Flush the toilet twice and wash your hands thoroughly after urinating. Avoid close contact with small children and pregnant women 24 hours following the scan.
  • You will need to discuss your scan result with your physician who referred you for the exam according to the appointment given.
In the PET-CT Centre (on the scan day)
  • You will be asked to change into our hospital gown and keep your belongings in the locker provided.
  • You will then be resting in our warm and quiet room and our technologist will then inject the FDG radiotracer through your IV line.
  • After FDG injection, you will have to wait for 50-60 minutes inside the room in order to get sufficient FDG distribution in your body. During this period, you should rest quietly and minimize your movement.
  • You will then be asked to drink a cup of water and void before commencing the scan.
  • In some circumstances, a catheter may be inserted into your bladder by our trained personnel.
During the PET-CT scan
  • You will be directed to the scanner room 50-60 minutes after FDG radiotracer injection.
  • You will be lie on a table which will pass slowly through a large opening in the scanner.
  • You will be asked to lie perfectly still throughout the procedure, so that blurring does not occur.
  • You will be closely observed at all times through a CCTV even though you will be alone in the room. If you have any discomfort during the scan, you can communicate with the technologist through the mounted intercom.
  • The CT exam with or without IV contrast will be done first, followed by the PET scan.
  • Total scanning time is approximately 30 minutes.

What will you expect when your physician ordered a PET-CT scan?

You will be given an appointment and receive specific instructions about some preparations that you must follow strictly before your scan. You should inform your doctor of the following when he / she ordered a PET-CT scans:

  • Is there any possibility that you may be pregnant.
  • What medications that you are currently taking, including vitamins and herbal supplements, recent illnesses and other medical conditions.
  • If you are breastfeeding at the time of your exam, you should ask your doctor ordering the exam how to proceed. It may need to pump breast milk ahead of time and keep it on hand for use after PET radiopharmaceutical and CT contrast material are no longer in your body.
  • If you are diabetic and what type of diabetic medications are you taking.
  • If you have any history of asthma or allergies, especially to contrast material, medications, iodine or seafood.
  • If you are claustrophobic.

How should I prepare for a PET-CT scan?

  • You are not allowed to consume any food, sugar and any liquids that contained sugar 6 hours prior to your appointment. Instead you are encouraged to drink plenty of plain water. In other word, you are only allowed to drink plain water on your scan day.
  • Do not consume alcohol, sweets, chewing gums and avoid strenuous exercise 1 day before your scan.
  • Take your regular medications at your usual time, except insulin or metformin (discuss with your doctor if you are on insulin or metformin).
  • Bring previous imaging films and results especially CT and MRI if you have any.
  • Do not bring children and pregnant woman with you on the day of your scan.

How is the procedure performed?

If you choose to be admitted 1 day before the scan (Preferably to be admitted for better patient management)

  • Your diet will be planned and ordered by our Dietitian. You can only consume the food that we provide to you.
  • You will need to rest in the ward and avoid strenuous exercise.
  • On the day of your scan, a nurse will insert an intravenous (I.V) line into your vein in your hand or arm and followed by IV drip administration of normal saline. You will then be resting in the ward until called down to the PET-CT Centre.
  • You will be discharge from the ward once you had been called down to PET-CT Centre. Therefore please arrange someone to pick you up after the scan.

If you choose not to be admitted (Any physical activities may delay your scan time)

  • You must plan your own diet and avoid food that contained sugar, high fiber and high carbohydrate.This diet plan must follow strictly 1 day before your scan. You may refer to the following diet:
You may eat the following:

Eggs, white bread, low fat plain yogurt, baked or boiled chicken, well-cooked potato, grilled or steamed fish and shrimp, clear soup or broth and all seafood. You may take egg sandwich as your breakfast, chicken chop as your lunch and fish and chips as your dinner.

Please avoid the following:

Red meat, whole meal or whole grain bread, oat, cereals, rice, noodles, yellow cheese, fruits or fruit juices and all vegetables.

  • You need to be in our hospital by 9.00am on your scan day. Please present your appointment card and register in our registration counter.
  • You will then be directed to our out patient department for observation, then to our PET-CT Centre.
  • A nurse will insert an intravenous (I.V) line into your vein in your hand or arm and followed by IV drip administration of normal saline.