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F-18 FDG PET CT scan: Instruction for patients

This leaflet provides information to patients undergoing a whole body / regional FDG PET CT scan.

What is a PET CT scan?

PET CT scan is a diagnostic procedure used to visualize metabolic activity of body tissues using radio-active glucose. The PET CT scanner, then generates images useful for the diagnosis and treatment.

How long is the PET CT scan procedure?

The entire procedure may take 2-3 hours, during which actual scan acquisition will be for 15-20 minutes only.

There are two stages of the PET/CT exam:

  1.  Injection of the radio-pharmaceutical FDG, following which you have to wait 45-90 minutes in isolation room, for your body to metabolize the FDG.
  2.  You will be escorted to the PET CT scanning room, where you will be asked to lie down on PET/CT scan table. The scan will take approximately 15-20 minutes.

How do I prepare for FDG PET CT scan?

  • No strenuous exercise for 48 hours before the scan.
  •  Overnight or minimum 4 - 6 hours fasting is required prior to appointment time (except diabetic patients)
  •  Please note: 4-6 hours fasting is mandatory for good quality of scan. Fasting less than 4 hours can cause deterioration of the scan quality andwe may have to repeat your scan
  • Patients are requested to report for the scan, 30 min prior to the appointmen time.
  • Drinking of plain-water is allowed. NO SUGARY DRINKS ARE ALLOWED. There is no need to hold urine.
  •  Patients are instructed to bring recent Blood urea and S. Creatinine reports (maximum one month old) and all their previous investigations, discharge summaries and physician's note. Please carry the CDs of previous PET CT scans along with you for comparison, if applicable.
  • Preferably, remove all jewellery (chain, bangles, ear rings, nose pin) and leave at home.
  •  Please inform the reception / Doctor If you are pregnant, breast feeding or allergic to contrast medium or any other medicine, before undergoing the scan.
  •  Please note: Occasionally, if the synthesis of FDG fails or due to some unexpected technical problem in PET CT machine, we might have to reschedule your test without any prior information.

Additional instructions for diabetic patients

  • Diabetic patients should inform us their blood sugar report in advance. Patient should bring all the diabetic medicines along with him / her.
  • Blood glucose level should be less than 180 - 200 mg/dl, else we may have to delay or postpone your scan.
  •  Patient must take light breakfast along with their anti-diabetic medicine 4- 6 hours prior to the scheduled time and come for the scan at least 2 hours prior to the scheduled time.

Additional instructions for admitted patients:

Stop dextrose injection 4 hours prior to appointment time.

Appointment booking:

  • Note: You are required to pay advance money during booking an appointment for the radioactive medicine (FDG) which will be specifically ordered for you and has a very short half-life (~ 2 hours). Hence, please keep your appointment on time. If you cannot keep your scheduled appointment, please call our office at-least 24 hours in advance, else the advance deposited will neither be refunded nor be adjusted against any other services./li>
  • Who can accompany me for the scan?


    We would prefer that you do not bring more than one person with you. Avoid bringing children or pregnant ladies with you.

  • When can I expect the results of my FDG PET CT scan?


    You will receive the results between 4 - 5 PM on next working day of your scan. The report will be accompanied with scan films and CD / DVD.

*If you have any further questions, please feel free to contact the Nuclear Medicine Department, Manipal Hospitals, Dwarka on 011-41275305, 011-41274251 between 9 AM – 5 PM (Monday-Saturday).




Consultant and Head
Nuclear Medicine
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