Generally, you will need to fast for several hours before the PET scan. This means no eating any food or drinking any liquids containing sugars. It is ok to drink plain water during this time and we recommend you drink at least 500mls of water before you arrive for your appointment.
Do not eat or drink anything, except water, for 6 hours before the exam. You may drink water, as much water as you can would be helpful, until arrival. Routine medications may be taken, unless you have been instructed otherwise.
Avoid exercising 24 hours before the scan. Follow a special diet for 12 to 24 hours before the scan. Don't drink or eat anything, except water, for 6 hours before the scan.
PET appointment. You should have nothing to eat or drink except water for at least 4 hours before your appointment time. This includes chewing gum, hard candy, breath mints and tobacco products.
Can I brush my teeth before a PET/CT scan? Normal brushing without swallowing mouthwash or toothpaste within the four hour preparation timeframe will have no effect on the outcome of your PET/CT scan.
Specific protocols may vary, but generally a PET scan follows this process: You will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan. If you are asked to remove clothing, you will be given a gown to wear.
12 hours before your appointment:
You will be asked to eat a low carbohydrate diet. Foods that can be eaten include: meat, hard cheese, tofu, eggs, butter and vegetables with no starch. Some foods that are NOT allowed include: cereal, pasta, milk, breads and other sugars.
Don't eat or drink (except water) for at least 6 hours before this test (e.g., no coffee, tea, juice, milk, gum or candies). take your regular medicines with water. Limit the amount of carbohydrates you eat the day before your test (e.g., bread, pasta, cereal, potatoes, rice, sugary foods).
The Day Before Your PET/CT Scan
Avoid all caffeine and de-caffeinated beverages for 24 hours prior to exam. It is important that you stay well hydrated.
The radioactive tracer gives off very small levels of radiation that go away very quickly. As a precaution, you should avoid close contact with pregnant women, babies and young children for 6 hours after the scan. You need someone to take you home and stay overnight if you've had medicine to help you relax (sedative).
During the procedure
It takes about 30 minutes to complete a PET-CT scan and 45 minutes for a PET-MRI scan. The machine makes buzzing and clicking sounds. The test is painless. If you're afraid of enclosed spaces, you may feel some anxiety while in the scanner.
You shouldn't experience any side effects after having a PET scan and can usually go home the same day. The results of your scan won't usually be available on the same day.
You will need to wait at the facility for one to two hours so your body can absorb the tracer, and you should rest quietly during this period. Before the scan, you will have the opportunity to ask your technologist any questions you may have about the procedure.
If you're having a brain PET-CT, it is important to limit brain activity before your scan. Your nurse may tell you not to read or listen to music while you're waiting for your scan. Your care team will ask you to urinate (pee) just before your scan.
Wear warm, comfortable clothing without metal fasteners. You may be asked to remove belts, jewelry or other metal objects. The remainder of the examination is performed similar to the Whole Body FDG PET/CT. There is no oral or intravenous contrast given for this exam.
Non-steroidal anti-inflammatory agents (Motrin, Ibuprofen, etc.) – Stop taking five days before your procedure.
The radioisotope that is used in PET imaging, fluorine 18 fluorodeoxyglucose or 18F-FDG, is a glucose transporter. This radioisotope will go to any metabolically active areas in the body. If the glucose levels are elevated from food or drink the patient consumed prior to the test, the level of insulin will increase.
Food that should be avoided Before PET Scan :
Fruits and Vegetables- All fruits, potatoes, corn, carrots, legumes (other beans), tomatoes, peas, squash, veggie burgers. Dairy Products- Milk, yogurt, high fat cheese.
PET/CT SCAN DIET INSTRUCTIONS
Avoid food and drinks that contain sugar or carbohydrates for at least 24 hours before your scan. This will help to make sure that your images are of the best quality and help prevent having to reschedule your scan because of a blood sugar that is too high.
Drinking plenty of fluid after the scan can help flush it from your body. As a precaution, you may be advised to avoid prolonged close contact with pregnant women, babies or young children for a few hours after a PET scan, as you will be slightly radioactive during this time.
Though most cancers are picked up on PET CT, there are a few which do not. The most important of these would be cancer of stomach (signet cell type). In such cases performing this test would be waste. However, there are cancers which are very sensitively detected which include lymphoma, GIST, etc.
After the PET-CT scan
You can do normal activities after the scan. This includes driving. The staff will tell you to drink several glasses of water. This helps wash the radioactive substance and dye out of your body.
The major drawback to standard PET is that the images are of substantially lower resolution than, for example, those of CT and MRI, and PET is generally poor at delineating anatomic detail.