🩺 Preparing for Your FDG PET/CT Scan for Cardiac Sarcoidosis
This specialized scan helps your doctor assess inflammation in the heart muscle caused by Sarcoidosis. To ensure the highest quality images, a specific and strict preparation regimen is essential. Please read these instructions carefully.
Why is Specific Preparation Required?
An F-18 FDG PET/CT scan uses a small amount of radioactive glucose (sugar) tracer. Normally, your heart muscle uses fatty acids for energy, but it can switch to using glucose. For this specific scan to work correctly, we must minimize the amount of glucose your normal heart muscle takes up so that the tracer highlights only the areas of inflammation related to Sarcoidosis.
The strict low-carbohydrate diet and prolonged fast force your heart muscle to use fat instead of sugar, allowing the tracer to focus on the active Sarcoidosis lesions.
🚨 Essential Preparation Instructions
Dietary Preparation: 24–72 Hours Before the Scan
You must adhere to a strict low-starch (low-carbohydrate) diet—often called a “Keto” diet—for 24 to 48 hours before your scheduled study. This is very important; please make sure you understand this instruction. If possible, following the diet for 72 hours is even better.
Foods to AVOID (Not Allowed) include: Bread, pasta, rice, cereal, crackers, potatoes, corn, peas, sugar, sweets, honey, milk, yogurt, and fruit/fruit juices.
Fasting and Hydration
Prolonged Fast: You must be NPO (nothing by mouth)—no food, sweets, gum, or mints—for 12 to 18 hours before the scan.
Water: You can drink water.
Caffeine: No caffeine is allowed for 6 hours prior to the study.
Exercise Restriction
Avoid all strenuous exercise for 24 to 48 hours prior to the PET/CT scan.
Medication Instructions (Especially for Diabetic Patients)
It is critical to follow these instructions exactly and to confirm them with your nuclear physician.
Medication Type | Instructions
Metformin | May be continued the day before the study, but should not be taken on the morning of the study.
Long-Acting Insulin (e.g., Protophane, Actraphane) | No long-acting insulin may be taken 48 hours prior to the study.
Fast-Acting Insulin (e.g., Actrapid) | No fast-acting insulin may be taken on the morning of the study.
Scanning Procedure: What to Expect
1. Injection: A small dose of the radiopharmaceutical (F-18 FDG) will be injected.
2. Uptake Period: The PET CT scan is performed 1 hour after the radiopharmaceutical is injected. You will rest quietly during this time.
3. Scanning: Yours arms will be positioned up above our head during the scan. The scan will run for approximately 20-minutes.
4. Scan Extent: The images will be focused over the chest (dedicated image), but a whole-body PET-CT might also be indicated.
After Your Scan
You can generally resume your normal diet, activity, and medication schedule immediately after the scan. Please drink plenty of fluids to help flush the small amount of remaining tracer out of your system.
