Foods to Eat and Foods to Avoid Before a PET Scan

A positron emission tomography (PET) scan is a nuclear diagnostic tool that examines body tissue functioning, such as blood flow, oxygen use, and sugar metabolism, to help doctors diagnose and treat disease.

To do a PET scan, a healthcare provider injects a small amount of radioactive glucose into a vein, which allows extremely small cancerous tumors and changes in the heart and brain to show up on the scan.

It's important to follow the specific pre-PET scan diet your doctor recommends to allow proper distribution of glucose throughout your body.

Types of PET Scans

There are a few types of PET scans:

Different types of PET scans may require different preps, so check with your doctor to be sure about which type you're scheduled to receive.

Foods to Eat Before an FDG-PET Scan

Foods to eat before an FDG-PET scan include:

• Protein foods, such as nonbreaded chicken, beef, turkey, pork, lamb, ham, hot dogs, lunch meat, fish, shellfish, tofu, most nuts, sunflower seeds, eggs, and unsweetened peanut butter
• Vegetables low in carbohydrates, such as green beans, broccoli, cabbage, cauliflower, celery, asparagus, cucumber, lettuce, mushrooms, and spinach
• Dairy products low in carbohydrates, such as hard cheese, sour cream, eggs, and butter
• Condiments low in carbohydrates, such as mayonnaise, salad dressing, oil, vinegar, mustard, olives, and dill pickles
• Beverages low in carbohydrates, such as diet soda, water, or sugar-free Crystal Light

Foods to Avoid Before an FDG-PET Scan

Before your FDG-PET scan, avoid anything containing glucose and most processed foods, including "low-carb" versions, for 24 hours before your scan.

Foods to avoid the day before an FDG-PET scan include:

• Vegetables such as potatoes, squash, carrots, peas, tomatoes, and corn
• Fruits, including all fruit and fruit juices
• Grains, including rice, rice cakes, bread, breaded foods, crackers, and pasta
• Dairy products such as milk and ice cream
• Nondairy milks, such as almond, soy, or oat milk, and yogurts or frozen desserts made from them
• Legumes, including all beans and soybeans
• Beverages that contain alcohol or caffeine, including beer, wine, liquor, coffee, and tea
• Condiments that contain carbohydrates, such as ketchup, syrups, jams, sauces, and gravies
• Snack foods that contain carbohydrates, such as chips, pretzels, candy, gum, cough drops, and breath mints

For the six hours preceding your FDG-PET scan, don't chew gum or eat or drink anything except water.

For best test results, make sure you're well hydrated.

Foods to Avoid Before a Myocardial Perfusion PET Stress Test

If you're taking a beta-blocker or a calcium channel blocker, consult your doctor well before the scan to discuss when to stop taking these medications.

For three hours before the scan, don’t eat anything or drink anything except water.

How to Prepare for a PET-CT Scan

A PET-CT scan requires avoiding the same foods as an FDG-PET scan in the 24 hours before the scan as well as consuming nothing but water for the six hours before the scan.

If You Have Diabetes

People who have diabetes should consult their doctor about how to prepare for a PET scan at least two weeks before the scan, as changing their diet may also require changing their diabetes medication regimen.

The Takeaway

• PET scans are diagnostic tools that require specific dietary preparations, sometimes up to 24 hours before the scan.
• Before an FDG-PET scan, you’re advised to drink extra fluids, avoid sugar and high-carbohydrate foods, and consume protein sources, like chicken and fish, as well as low-carbohydrate vegetables.
• People with diabetes should consult their doctor at least two weeks before a PET scan, as dietary changes may necessitate adjustments to their diabetes medication.