PET-CT scan for cardiac sarcoidosis - 18F-FDG

What is a PET-CT scan?

PET-CT (Positron Emission Tomography and Computerised Tomography) is a scanning method that allows us to see how organs are working. PET-CT helps us identify organs or tissues that are not working normally. The body is imaged following the injection of a radioactive tracer. The most commonly used pharmaceutical in PET is Fluorine-18 fluorodeoxyglucose (FDG), a slightly radioactive form of sugar. This provides important information about many conditions affecting different organs and the images allow your doctor to plan your treatment more effectively.

What are the benefits?

PET-CT combines two types of imaging in one scan. Your doctors get functional information from the PET scan as well as organ anatomy from the CT scan to check if your organs and tissues are functioning normally.

Are there any side effects?

The scan involves an injection of a small amount of a radioactive tracer which will remain in your body for a few hours. This radiation can cause cell damage that can, after many years or decades, contribute to the development of cancerous cells. This procedure carries only a very small chance of this happening to you.

Very rarely there may be bruising at the site of the injection.

Your doctor has considered the risks and benefits of having this test before referring you to us. The benefits of the test outweighs the potential risks.

Alternatives

This scan forms part of a series of investigations your doctor will be undertaking. There is no equivalent scan we can use.

Do I need to confirm my appointment?

No, but the tracer we use will be ordered for you and cannot be used for any other patient. It is important you inform the department if you are unable to attend your appointment. Please help us to conserve valuable NHS resources.

Your scan will take place in the PET-CT department of Addenbrooke’s Hospital. It is vital that you arrive on time for your appointment as the radioactivity has a very short shelf life. If you are late for your appointment we may not be able to proceed with your scan.

Please also be aware that the tracer is produced off-site and delivery can sometimes be delayed because of production or transportation issues.

Please call us on 01223 349222 to inform us if you:

• have had or are expecting chemotherapy within three weeks of your appointment
• have had radiotherapy within the last three months
• have had surgery within the last three months
• are taking oral steroids
• have had a recent infection
• are pregnant, breast feeding or have any young children at home
• are diabetic
• have any disability or special needs requiring ramp access
• have been told you have difficult veins to cannulate
• weigh over 100kg (16 stone)
• are claustrophobic
• have any difficulty lying flat for up to 20 minutes
• have any other appointments on the same day

Please let us know your list of medication, particularly steroid medication. If you are diabetic, take your diabetes medications with food. During the fast, please avoid taking insulin or any other medication that lowers your blood sugar.

Do I need to prepare for my scan?

Yes, this scan requires you to adhere to a high-fat, high protein, low-carbohydrate diet from the morning before to the day of your scan. You will then need to fast for 18 hours prior to your appointment time. This may sound like a very long time, but will basically mean that you will stick to the diet the day prior to your scan, with an early dinner, and then simply skip breakfast on the morning of your PET scan. During this whole period we would like you to keep well hydrated. Please see the Dietary Instructions at the end of this leaflet.

Avoid strenuous exercise for 24 hours prior to your scan appointment, e.g. running, cycling, horse riding or gym exercise.

Please consider leaving all jewellery at home as we will need to remove metallic objects for the scan if possible. We suggest wearing something loose and comfortable. If required, a hospital gown can be provided for the scan.

Can I bring someone with me?

Any friends or relatives bringing you to your appointment will not be allowed to stay in the unit due to limited waiting room space. Only an essential carer or interpreter is permitted. Please note that during your scan, they may be asked to wait outside the scan room due to the limited space.

Please do not bring children or pregnant friends or relatives with you.

Ensure that you adhere to current Trust COVID-19 guidelines regarding the attendance of appointments.

How long will I be in the department for?

You should expect to be with us approximately two hours in total. This includes explanation, preparation and scanning time.

What will happen on the day of my scan?

Once you arrive for your appointment you will be taken into the interview room and the procedure will be fully explained by one of our radiographers/technologists who will also take a brief clinical history. If you have any questions, this is a good opportunity to ask them.

A small needle will be inserted into a vein in your arm, hand or foot. Unfortunately we are not able to make use of Hickman lines or any other device that cannot be removed immediately after injection.

Your blood glucose level will be checked. We need your blood sugar to be at a fairly low level, which is the reason for the diet. If high blood sugar levels are detected, your scan will need to be rescheduled. If your blood glucose level is ok, we will give you a small amount of heparin to help highlight any areas of sarcoidosis in your heart followed by an injection of radioactive tracer.

You will then lie and relax quietly for 60 to 90 minutes before having the scan.

Just before your scan, you will be asked to empty your bladder and to remove all jewellery and metallic objects. We will then ask you to lie on your back on the scanner bed with your arms placed above your head. In certain circumstances, we may also scan you with your arms by your side. Most scans last between 10 and 20 minutes.

What happens after my scan?

You are free to go home. You may eat and drink as normal. Continue to drink plenty of fluids for the remainder of the day and empty your bladder frequently.

Please avoid close contact with pregnant women and young children for six hours after your scan.

If you are breastfeeding, we recommend that you:

• Express and appropriately store at least one feed before your appointment
• Breastfeed your child before your appointment
• Express as much milk as you can in the 2 hours after your scan and discard the milk
• Ideally, have someone else bottle feed the stored milk to your child until the end of your six-hour contact restriction

When will I get my results?

Your results will be sent to the doctor that requested your scan. Results are usually with your doctor within a week or two, often much sooner.

If you have a further appointment with your doctor, please let us know the date when you attend for your scan.

Further information

For further information, you can contact the PET-CT team on 01223 349222.

Dietary instructions

For your PET scan, we need you to follow a low carbohydrate, high fat, high protein diet before starting your fast for 18 hours prior to the time of your appointment.

For example, if your PET-CT scan is scheduled at 11:00; finish your special dinner by 17:00 on the day before the scan and skip breakfast on the day of your scan. You are allowed to drink liquids but please make sure there is no sugar in the drinks.

Please note that sugars in any form, including natural sugar in fruit, is strictly forbidden during the diet period.

Please find below lists of foods and drinks that are allowed and not allowed. We have also provided sample diets for the day before the procedure if you need some ideas.

Foods/drinks allowed

Beverages

Water, mineral water, sparkling water, coffee, tea, herbal tea (without sugar), iced tea

Condiments and seasonings

Salt, pepper, any natural herbs or spices

Dairy products

Creme fraiche, double cream, sour cream, butter, eggs, any non-processed cheese

Fats/Oils

Animal fats that are part of the meat you eat, butter/margarine, vegetable oils (olive, peanut, walnut, sesame, sunflower, rapeseed)

Fish/Shellfish

Any non-processed fish/shellfish

Meat/Poultry

Any non-processed meat or poultry, eggs

Vegetables

Asparagus, artichokes, aubergines, broccoli, bok choy, brussel sprouts, bean sprouts, celery, cucumber, courgettes, cauliflower, fennel, garlic, kohlrabi, lettuce, leeks, mushrooms, okra, olives (non-processed), peppers, radishes, squash, scallions, shallots, spinach, tomatoes, turnips, and any fresh herbs.

Sweeteners

Acesulfame-K, aspartame (NutraSweet), saccharine (Sweet ‘N Low), stevia, sucralose (Splenda)

Foods/drinks NOT allowed

This is not an exhaustive list but if in doubt, please make sure that the carbohydrate content of the food you may consume is very low/none.

Beverages

Any fizzy pop, any beers/ales, wines or spirits, drinking chocolate

Condiments and seasonings

Tomato ketchup, barbecue sauce, Worcester sauce, cocktail sauce, honey mustard, any jams or syrups

Dairy products

Milk, any processed cheese (e.g. Dairy Lea, Babybel)

Fats/Oils

Lard, dripping

Fish/Shellfish

Any processed fish or shellfish

Meat

Deli meats (eg pastrami, salami, chorizo, pepperoni), any processed meats

Poultry

Any processed poultry

Vegetables

Potatoes, beans, lentils, peas, beetroot, carrots, cabbage, parsnips, plantain, pumpkin, swede, sweet potatoes, sweetcorn, turnips, yam

Other foods

Please avoid any pasta, bread, cereal, rice, fruit, chocolate, sweets, chewing gum etc.

Sample menu

Please see below a choice of sample menus for your meals the day before your scan.

Choose one option from Group A and any amount of vegetables from the list from Group B to make up your meal.

Group A

1) Coq au vin (Meat option)

Make the recipe as below and weigh out 250g (medium portion).

(250g = 1 serving)

Recipe

• 100g bacon rashers
• 1000g chicken leg quarters
• (weighed with bone)
• 50g butter
• 50g flour
• ½ tsp salt
• 600mls red wine
• ¼ tsp black pepper
• 100g shallots
• 1 tsp dried mixed herbs
• 100g mushrooms

Coat the chicken in seasoned flour. Brown the bacon and chicken in butter. Add the shallots, mixed herbs and red wine, cover and simmer for 35-45 minutes. Add the mushrooms and cook for another 20 minutes. The wine in this recipe is acceptable as it has been heated during cooking.

2) Grilled salmon - (Meat free option)

(150g equal to 1 large salmon steak)

3) Quorn pieces - (Vegetarian option)

Fry 215g Quorn in 15g butter (use vegetarian butter) or 15g vegetable oil.

4) Omelette - (Egg option)

Make the recipe as stated below.

Recipe = 1 serving

• 4 eggs
• 10mls water
• 10g butter
• 60g Cheddar cheese
• ½ tsp salt
• black pepper for seasoning

Beat eggs with salt, pepper, water and cheese. Heat the butter in a pan. Pour in the mixture and stir until it thickens evenly. While still creamy, fold the omelette and serve.

Group B

• Broccoli
• Cauliflower
• Celery
• Courgette
• Aubergine
• Cucumber
• Lettuce
• Curly kale
• Spinach
• Mushrooms
• Garlic
• Pepper
• Radish
• Watercress

Eat raw or cook the vegetables by steaming, boiling or microwaving. Do not add any additional butter or oil during the cooking process. Seasoning such as salt, pepper or herbs can be used.