A PET/CT scan is an important diagnostic procedure in nuclear medicine, used to visualize metabolically active tissues. It involves the use of sugar (glucose) molecules labelled with the radiopharmaceutical FDG. The labeled glucose is incorporated into the actual cell, and once the cell has metabolized the glucose, the low-level radioactivity can be detected by the PET/CT scanner. This then generates images used for diagnosis and treatment. To ensure the best possible results from your PET/CT scan, it's crucial to adhere to specific preparation instructions, especially regarding diet. This article provides a detailed guide on how to prepare for your PET scan, covering dietary restrictions, medication guidelines, and other essential instructions.
Understanding the PET/CT Scan Procedure
The PET/CT imaging procedure typically takes about 2-3 hours. During this time, you will receive an injection of the radiopharmaceutical FDG. Following the injection, there is a waiting period of 60 minutes, during which you will rest comfortably to allow your body to metabolize the FDG. Before the scan begins, you will be asked to empty your bladder.
The scan itself involves lying down on a table that passes slowly through the PET/CT scanner, which resembles a CT scanner. The images produced help visualize metabolically active tissues, aiding in diagnosis and treatment planning.
24-Hour Dietary Restrictions
For 24 hours before your PET/CT scan, it's essential to follow a very limited carbohydrate (no sugar) meal plan. This helps to ensure that the radiopharmaceutical FDG is absorbed correctly. If anything is eaten within four (4) hours prior to the exam, there is a significant decrease in the absorption of the radiopharmaceutical FDG. All patients must follow the 24-hour diet.
Important Considerations for Diabetics
Oral Diabetic Medications
If you are diabetic and take oral diabetic medications, the instructions vary depending on the timing of your appointment:
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- Morning Appointment: Do not eat or drink anything for 4 hours before your exam except water and non-diabetic medicines.
- Afternoon Appointment: You may have a light breakfast and take your morning medications - including oral diabetic medication, as long as it is not four (4) hours prior to your appointment.
Subcutaneous Insulin Dependent Diabetics
If you are a subcutaneous insulin dependent diabetic, it is preferable to schedule your appointment for late morning or afternoon. On the day of your scan:
- You may eat a light breakfast and take 1/2 of your regularly prescribed insulin, as long as it is not four (4) hours prior to your appointment.
- Do not eat or drink anything except for water or black coffee for four (4) hours before your exam.
General Guidelines for Diabetics
It is important for all diabetic patients to stay well hydrated. Any non-diabetic medications may be taken the day of your scan. The team will test your blood glucose level, aiming for a level between 70mg/dL and 200mg/dL.
Key Guidelines to Follow
- Hydration: It is important that you stay well hydrated.
- Clothing: If possible, do not wear clothing with belts, zippers, snaps, or metal of any kind to your appointment.
- Warmth: Try to stay warm on the day of your scan.
- Exercise: No strenuous exercise for 48 hours before the scan.
- Medications: Any non-diabetic medications may be taken the day of your scan.
What to Expect During the Scan
Upon arrival, the team will test your blood glucose level, looking for a level between 70mg/dL and 200mg/dL. After the injection, you may be given one cup of an oral barium contrast to drink. You will then rest quietly in a reclining chair for 75 minutes.
Additional Information
Prior to your appointment, you will receive a call from a technologist at the Imaging Center to answer any questions you may have about your study and confirm preparation instructions. If you cannot keep your scheduled appointment, please call 501.906.3000 at least 24 hours in advance.
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