PET-CT Prep & Diet Instructions


PLEASE NOTE: These instructions are to be used with common sense. Specifically, these are general guidelines and if anything pertaining to the dietary instructions could be harmful to you, do not eat it. Also, do not discontinue any prescribed medications that you are taking. If you are a diabetic, please note the specific diabetic instructions below and be aware that proper management of your blood sugar is more important than strict adherence to this diet. In general, however, this diet is safe, particularly for a 1-day period, even for most diabetics and patients with high cholesterol.

1. Your PET-CT scan provides a picture showing where certain molecules are in your body; in most cases, where glucose or “sugar” is located. This is greatly affected by the level of sugar in your blood, therefore your diet the day before the scan makes a BIG difference in the quality of pictures that we get. Obviously, it is very important for you to get the best scan possible, so please try to follow this diet as closely as possible.

2. Do not eat or drink anything other than water (no coffee, tea, juice, etc.) for the 6 hour period prior to your scan. Chewing gum or breath mints (even the diet kind) are also excluded. There is no limit on the amount of water you can drink (actually, the more water, the better). IF YOU ARE A DIABETIC: DO NOT EAT OR DRINK ANYTHING OTHER THAN WATER FOR 4 HOURS PRIOR TO YOUR SCAN.

3. The night before your scan, you can eat non-breaded meat and entrees such as:

  • Grilled or pan-broiled steak.
  • Baked, broiled or boiled chicken.
  • Grilled or baked fish and shrimp, with or without butter or margarine.
  • Side items without carbohydrates, such as grilled or steamed asparagus or broccoli, sautéed mushrooms, and/or any GREEN vegetable or salad (NO CROUTONS), with non-white dressing, such as regular Italian or vinegar and oil). You may put butter or margarine on your food, but not cheese or gravy.
  • You may NOT eat the following:
    • Carbohydrates such as potatoes, pasta, rice, chips or bread.
    • Dairy products, such as milk, cream (or cream substitutes), ice cream, cheese, cheese dip, yogurt, whipped cream, etc.
    • Diet ice cream, ice milk, Cool-Whip, or other diet dairy products.

4. The day of your scan, as long as it is NOT less than 6 hours (4 hours if you are a diabetic) before your scan, you may have a breakfast of any style eggs, with bacon/sausage, and more water. No fruit juices.

5. No exercise of any sort for the 48 hours prior to the exam. This includes even nominal exercise such as golf and gardening.

6. If you are diabetic, your blood sugar must be below 200 in order for us to do the scan. Diabetic patients are encouraged to test their blood sugar before their appointment – if it is above 200, call us at the phone number listed below to cancel your scan. Do not eat or drink anything (other than water) in the 4 hours prior to your test time. You may drink as much water as you like AND YOU MAY TAKE THE MEDICATIONS THAT YOU NORMALLY WOULD TAKE, but with water only.

  • Take your ORAL diabetic medications no less than 4 hours prior to your scan time.
  • Take your INSULIN no less than 2 hours prior to your scan time.
  • Your diet prior to 4 hours from scan time should be high in protein (meats, cheeses, eggs). Avoid juices, breads & fruits.


  • You will be asked to change into a gown and remove any metallic jewelry.
  • You will receive an injection of a trace amount of radioactive glucose, which is distributed throughout the body.
  • About 30-60 minutes after the injection, you will empty your bladder.
  • Upon entering the PET/CT scanner room, you will see a large machine with a donut-type opening. You will be asked to lie on the scanner’s table. The procedure will be explained to you.
  • Once the scan is complete and the quality of the images is verified, you will be free to leave. We will then fuse your CT and PET images to provide our radiologist and your doctor with a combination of metabolic and anatomic information to better interpret your study.
  • Total estimated time of procedure: 15-90 minutes, depending on the type of scan you are having + 1 hour prior to accommodate the injection and waiting period.