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Understanding PET-CT Scan

What is  PET/CT Scan?

PET/CT is the most advanced medical imaging technique available today, combining Positron Emission Tomography with Computed Tomography. PET/CT combines the fine structural detail of CT with PET’s ability to detect changes in cell function. This combination allows for earlier and more accurate detection of disease than either CT or PET alone.


A PET/CT scan helps your physician diagnose a problem, determine the best approach to treatment or monitor your progress.



How does PET/CT work?


A form of radioactive glucose called FDG, which emits particles called positrons, is injected before a PET/CT study is done. The FDG molecules are consumed more in fast growing or active cells than in normal cells, resulting in concentrations of FDG and positrons. A PET/CT scanner detects where positrons are being emitted from within a patient and provides images that map the locations.


PET FDG mapping is combined with a CT image’s structural detail in order to identify both the presence of disease and its precise location.



Preparing for your PET/CT Scan


  • For 6 hours before your test, do not eat or drink (except water). Drink 8-16 ounces of water two hours before your scan. For the best quality imaging, please do not chew gum or ingest any sugar products (i.e. candy).
  • Your last meal before the scan should be high in protein and low in carbohydrates. For example, dinner might consist of steak, baked chicken, fish, cheese, asparagus,  broccoli or mushrooms. Breakfast could be eggs, bacon and/or sausage. No pasta, potatoes, rice or bread.
  • Continue to take any medication prescribed by your physician. If you have been advised to take your medications with food, eat a small amount of low carbohydrate food (i.e. cheese, peanut butter, etc.) preferably 2-4 hours before the scan.
  • Avoid caffeine, sugar, and tobacco for 6 hours prior to your exam.
  • Do not exercise 24 hours before your scan.
  • If you have diabetes, it is important that your blood glucose level remain below 200. The scan can not be performed if your blood glucose level is too high. If you need to eat during the six hours before your scan, eat small amounts of low carbohydrate food. If you have questions or concerns, call your physician or the PET center staff.
  • If you are pregnant, or think you may be, discuss this with your physician. Generally, PET/CT is not performed on women who are pregnant. If you are breast-feeding, you will need to discontinue breast-feeding for 2 to 3 days.

What to wear

Wear warm, comfortable clothes since the scanner room is cool. Avoid clothes with metal components.



Arrive on time


Please arrive before your scheduled appointment. If you must cancel or reschedule, please do so at least 24 hours before your appointment.



Your PET/CT Scan


After registering, you will go to a preparation area where a PET technologist will insert a small IV line into your arm. A small amount of FDG, a form of radioactive glucose, will be injected through the IV line. This is painless.


You will rest quietly without speaking for 45 to 60 minutes to allow the FDG to distribute in your body.


Your scan will take approximately 20 to 45 minutes.You will be at the PET Center for approximately 2 hours.



After your scan

You can leave immediately.Your activity will not be restricted. You may drive if you wish, resume your normal diet, exercise, and take all prescribed medications.


The PET/CT scan will be reviewed by a physician who will send a report to your doctor.Your doctor will contact you about the results of your PET scan.



To limit radiation exposure


As a precaution, avoid getting close to children or anyone who is pregnant for eight hours following the scan. Do not bring children with you to the PET Center. Flush your toilet twice for the rest of the day because your urine will contain radioactivity for about 8 hours.




Baptist Health Diagnostic Services Southland Drive

100 Southland Drive

Lexington, KY 40503


Fax: 859-260-5498





The American College of Radiology awards accreditation to facilities for the achievement of high practice standards in image quality, personnel qualifications, adequacy of facility equipment, quality control procedures, quality assurance programs and safety guidelines. Providing you with the finest care and service possible is our goal.


We encourage your comments on the care you receive as a patient. Should you have a suggestion, comment or question while you are here, please let us know or you may call 859- 260-6168 to speak with a patient representative. Thank you for letting us serve you.