What Happens if You Eat Carbs Before a Pet Scan

What Happens if You Eat Carbs Before a PET Scan?

A positron emission tomography (PET) scan is a diagnostic imaging procedure that uses a radioactive substance to visualize the functioning of tissues and organs within the body. It is commonly used to detect and evaluate various diseases, including cancer, neurological disorders, and cardiovascular conditions. To ensure accurate results, there are certain preparations that need to be followed before a PET scan, including dietary restrictions.

Carbohydrates are known to affect the results of a PET scan. When you consume carbohydrates, your body breaks them down into glucose, which is the primary source of energy for cells. During a PET scan, a radioactive substance called a tracer is injected into your body, which binds to glucose molecules. The scanner then detects the radiation emitted by the tracer, allowing for the visualization of areas with high glucose metabolism. If you consume carbohydrates before a PET scan, the increased glucose levels in your body can interfere with the accuracy of the scan.

Eating carbs prior to a PET scan can lead to false-positive or false-negative results. False-positive results may occur when the increased glucose levels cause normal tissues to be falsely perceived as areas of high metabolic activity. Conversely, false-negative results may occur when areas of actual disease are masked by the high glucose activity caused by carbohydrate consumption.


1. Can I eat anything before a PET scan?
It is generally recommended to follow a low-carbohydrate diet for at least 24 hours before the scan, avoiding foods such as bread, pasta, rice, and sugar.

2. What can I eat before a PET scan?
You can consume foods that are low in carbohydrates, such as lean proteins (chicken, fish), vegetables, and healthy fats (avocados, nuts).

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3. How long before a PET scan should I avoid carbs?
It is recommended to avoid carbs for at least 24 hours before the scan.

4. Will a small amount of carbs affect the scan results?
Even a small amount of carbs can affect the accuracy of the scan, so it is best to strictly adhere to the recommended dietary restrictions.

5. Can I drink water before a PET scan?
Yes, you can drink water before a PET scan, as it does not interfere with the results.

6. Can I have coffee or tea before a PET scan?
It is best to avoid coffee or tea that contains sugar or milk, as they may contain carbohydrates.

7. What if I accidentally ate carbs before a PET scan?
Inform your healthcare provider immediately so they can assess if rescheduling or adjusting the scan is necessary.

In conclusion, consuming carbohydrates before a PET scan can lead to inaccurate results. It is important to follow the recommended dietary restrictions to ensure the scan provides accurate information for diagnosis and treatment planning. Always consult your healthcare provider for specific instructions and any concerns regarding your upcoming PET scan.