The Importance of a Low Carb Diet Before a PET Scan

Positron Emission Tomography, commonly known as PET scan, is a diagnostic examination that involves the use of radioactive substances to visualize and measure metabolic processes in the body. It is often used to detect cancer, evaluate the progress of disease treatment, and diagnose neurological disorders and cardiovascular disease ¹.

Why a Low Carb Diet?

The effectiveness of a PET scan can be significantly influenced by the patient’s diet prior to the examination. This is because the radioactive substance used in the scan, known as FDG (Fluorodeoxyglucose), is a glucose analog. When consumed, carbohydrates break down into glucose in the body. High glucose levels can compete with FDG, potentially leading to less accurate scan results. Therefore, a low carbohydrate diet is recommended before a PET scan to ensure the best possible image quality ².

What to Eat and Avoid

For at least 24 hours before your scan, you should avoid foods and drinks that contain sugar or carbohydrates. This includes:

• Fruits and fruit juices
• Soft drinks
• Jellies
• Coffee with sugar
• Yogurt with sugar
• Desserts
• Candy
• Alcohol
• Bread, rolls, cakes, tortillas
• Rice, pasta, crackers
• Potatoes or corn
• Snack chips (corn, potato, popcorn)
• Pastries
• Oatmeal or any cereal
• Pizza dough

Your meals during this period should consist of proteins and non-starchy vegetables. Here are some examples of foods that are allowed:

• Fish (Tuna or grilled fillets)
• Chicken (avoid breading or fried chicken)
• Pork (including bacon and ham)
• Eggs
• Cheese and Milk
• Beans
• Non-starchy vegetables (no potatoes or corn)
• Nuts (not honey roasted)

Special Instructions for Diabetic Patients

Diabetic patients need to take extra care in managing their blood sugar levels before a PET scan. High blood sugar levels can interfere with the scan’s results. As a general rule, diabetic patients must be fasting (meaning you can only drink water) for at least six hours prior to the PET/CT scan. You must not have taken insulin within four hours prior to the scan ³.

Other Important Considerations

In addition to dietary modifications, there are other important considerations to ensure the effectiveness of your PET scan:

• Avoid strenuous physical activity a day before the scan as it can affect the scan results ⁴.
• Stay warm for at least 24 hours before your scan. This helps the quality of the PET images ⁵.
• Hydrate well. Unless your doctor has told you to limit your fluid intake, please continue to drink plenty of water up to your exam time ⁶.
• Dress warmly on the day of your scan. To get the best scan results, you must not be chilled prior to or during the preparation for your scan.
• Inform your healthcare provider if you are pregnant, a nursing mother, claustrophobic, diabetic, or if you have any special needs ⁷.

Remember, the goal of these guidelines is to ensure that your PET scan provides the most accurate and useful results possible. Always consult with your healthcare provider or a dietitian if you have any questions or concerns about your diet before a PET scan.

Footnotes

1. https://www.radiologyinfo.org/en/info/pet
2. https://www.spectrumhealth.org/services/imaging-and-radiology/nuclear-medicine/pet-ct-scan/diet-plan
3. https://www.southwesthealth.org/radiology/pet-scanning/pet-scan-for-diabetics/
4. https://www.mdanderson.org/cancerwise/getting-a-pet-scan-what-to-expect.h00-158986656.html
5. https://www.spectrumhealth.org/services/imaging-and-radiology/nuclear-medicine/pet-ct-scan/diet-plan
6. https://radiology.ucsf.edu/patient-care/prepare/pet-ct
7. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/10/guidelines-for-diagnostic-imaging-during-pregnancy-and-lactation