FDG Whole-body PET-CT

Downloads

For most essential points to best prepare for the procedure, please download the patient information brochure (PDF).
For a more elaborate explanation of the procedure and related points, please continue to read ahead.

It stands for 'fluorodeoxyglucose'.
A radioactive form of molecule called ‘FDG’ resembling glucose is injected into the vein.
Fast dividing and excessive energy consuming cells accumulate and retain more FDG compared to other normally functioning cells.
Cancer cells and sites of inflammation show greater FDG concentration, and stand out on the PET scan.
Various organs of the body block different amounts of X-rays depending on their density. A CT scan gives idea of density, shape and size of these organs. Iodinated contrast typically used as part of CT scan improves recognition of organs and diseased parts within based on their pattern of blood supply.
Both PET and CT scans are performed on the same scanner, and fused using software to produce images that give information about both function and form of organs and diseased parts (if any).

Prior appointment is a must as FDG spontaneously decays, and is not readily available at the diagnostic facility.
Patient must not be pregnant.
If breast feeding, please inform the staff for further directions.
Fasting blood glucose level should be preferably lower than 200 mg/dL. If the level is higher, please consult the doctor managing your diabetes.
Recent (within past 7 days) serum creatinine level must be known.
6 hours’ fasting before scan.
No diabetes related drugs (oral medications or insulin) for 6 hours before scan.
Avoid strenuous exercise for 1 day.
Avoid carbohydrate-rich food for 1 day.
Please let the staff know at the time of appointment if the patient is unable to lie still for ~20 min, has breathing difficulty, or might need special medical attention for the duration of visit.
Have at least 1/2 litre water within an hour before reporting for the scan. There is no need to hold urine.
There is no need to hold urine before reporting for the procedure.
Wear loose-fitting but warm clothes.
Do not bring expensive jewellery or accessories along with you for the scan.
Proof of doctor's request is necessary for starting the procedure.
The patient must be accompanied by a responsible carer.

Patient registration and consent.
Handing over medical documents to the staff.
Blood glucose level is measured through finger prick method.
Oral contrast (typically 500 to 1,000 mL) to be had over next 45 min to 1 hour.
Intravenous (IV) access is established (in form of cannula).
FDG is injected through the cannula.
Waiting time of ~1 hour (± 15 min) to allow sufficient time for FDG to be taken up and eliminated by all organs. Pass urine just before the scan, and also before that (if needed).
‘Whole-body’ procedure typically includes scanning from head to upper thigh as the patient lies still on their back. IV contrast is injected through the cannula. Time taken on the scanning table is ~15 min. Patient may have to hold breath for few seconds.
Scan is briefly reviewed for adequacy and quality. Occasionally, a scan may be repeated or scanning of additional body parts may be considered. If everything is to staff’s satisfaction, then the patient may leave.

Pain during IV cannula insertion.
There is risk of extravasation at the time of IV cannula insertion, FDG injection or injection of iodinated IV contrast. [Extravasation means that blood leaks through the walls of vein punctured by cannula’s needle].
Iodinated contrast is injected in relatively large volumes and at a high flow rate. This can cause sensation of warmth and pain at the injection site. Rarely, patients develop allergic reaction to the contrast in form of skin rash, breathing difficulty, dizziness, or loss of consciousness. IV contrast also mildly and transiently suppresses kidney function, but it usually recovers completely by itself, and patients do not experience any corresponding discomfort.
FDG does not cause any discomfort. It is injected in very minute quantity, so it does not alter function of any organ.

Typical: 3.5 hours.
Be prepared for: 5 hours (can be further prolonged in case of increased blood glucose level or other unforeseen events like malfunctioning of scanner, delayed delivery of FDG, etc.).

Maintain at least 1 metre-distance from pregnant ladies and children (below 10 years) for at least 5 hours after the scan.
Drink plenty of water throughout the day (3 to 4 litres).
Pass urine as frequently as possible.

Because of IV contrast, some patients experience headache or heaviness of head, which resolve within a day.
Oral contrast can cause watery motions or loose stools. This typically resolves by itself within a day.
Both FDG and X-rays expose the patient to ionizing radiation. However, radiation dose received as part of the entire procedure is not expected to cause any obvious harmful effect. Additionally, benefit from information received through the procedure greatly outweighs any theoretical risk associated with this radiation exposure.

Typical (for self-paying patients): 12 hours.
Be prepared for: 36 hours (especially if some patient data or past scan data are missing).
Credit patients will receive their reports from the respective referring hospitals.

For additional information, please visit the following links.