Preparing for a PET Scan: What I Wish Someone Had Told Me
When you are told you need a PET scan the last thing you need is a list of instructions without any explanation.
You are often already overwhelmed, tired, or mentally foggy because of stress, treatment, hormonal changes, or simply the weight of uncertainty.
In that state, vague rules like “avoid carbs” or “fast before the scan” do not feel helpful. They feel confusing.
If someone had explained the reason behind the instructions, the whole process would have made far more sense.
This is the guide I wish I had. It is practical, clear, and grounded in real experience.
What a PET scan actually does
A PET scan uses a glucose based tracer to show how active cells are in your body.
Cancer cells often use more glucose than normal cells, which is why preparation matters.
If you eat too many carbohydrates or sugar before the scan, your body uses that glucose instead. This can make the images less clear.
The goal is simple. Keep your blood sugar low and stable.
The Biggest Mistake People Make Before a PET Scan
Many people think they can just eat healthy.
The problem is that healthy often includes foods like fruit, yoghurt, oats, smoothies, or whole grains.
For a PET scan these foods can interfere with the results.
This is not about dieting. It is about biology.
What to Avoid Before a PET Scan
It’s important to check with your doctor but usually, for twenty four hours before your scan avoid:
Sugar and sweets
Bread, pasta, rice, cereal
Fruit and fruit juice
Milk and sweetened almond, oat, or other plant milks
Coffee or decaf coffee
Black, green, or any caffeinated tea
Soft drinks and energy drinks
Alcohol
Potatoes, corn, pumpkin
Sauces with sugar such as BBQ or teriyaki
Even small amounts can affect the scan.
What to Eat and Drink
Focus on protein, healthy fats, and low carbohydrate vegetables.
My food options
Eggs
Chicken, beef, lamb, fish
Cheese
Avocado
Nuts in small amounts
Leafy greens, broccoli, cauliflower, zucchini, mushrooms, cucumber
Drinks:
Water
Herbal tea, unsweetened (peppermint, chamomile, rooibos, ginger)
Unsweetened almond, coconut, or macadamia milk in small amounts
It does not need to be perfect. The goal is low sugar and low carbohydrates to help your scan be as accurate as possible.
Fasting Before Your Scan
Fasting is one of the most important parts of preparing for a PET scan.
Most imaging centres ask you to fast for six to twelve hours before your scan.
During fasting you can drink water freely.
Avoid all food, snacks, juice, milk, coffee, or tea.
My tips for fasting:
Schedule your scan in the morning if possible so fasting overnight is easier.
Stay hydrated with water.
Avoid chewing gum or mints with sugar.
Stick to your PET-scan-friendly foods and drinks the day before.
The Day of Your PET Scan
On the day of my PET scan, they first weighed me, measured my height, and checked my blood glucose. It was a lot to take in, and I already felt tired from everything else going on.
They placed a cannula into my arm, a small plastic tube that would later be used to inject the PET tracer.
Then I was taken to a small private room. The room is isolated because the tracer is radioactive and could be dangerous to others. It had a bed, a TV, and a remote, though the hospital wifi did not make it into the room. I’m not sure why but I assume that it was probably because the room had to be reinforced somehow for the radiation, but honestly, how could they possibly leave me to my own thoughts at a time like this?!
The machine delivered the tracer through the cannula while I watched tv. The tracer takes up to an hour to circulate through your body, which feels like a long time when you are trying to stay calm, but it is necessary for the scan to work properly.
Once the tracer had spread, I was taken into the scanner. The scan itself took about 20 each time, and honestly, the only hard part for me is lying still. It was painless, but I could feel the weight of waiting for results.
Staying Calm During a PET Scan
I have had three PET scans now, and honestly, they never get easier. I am actually having another PET scan tomorrow morning. I planned to write this blog both to help me work through everything and to share it with others who might be going through the same thing and wondering what it feels like.
The hardest part for me has always been staying calm, especially because I have claustrophobia. Surprisingly, the PET scan machine itself is not too bad. What is hardest is the waiting, the uncertainty, and just being in the process.
I have learned to focus on my breathing. I take big, deep breaths. The first scan I counted 132 breaths. Long, deliberate breaths. It is a way to tell my body that I am okay, that I am safe.
I have realised that I can either make myself miserable or I can make myself strong. The effort is the same. Focusing on my breathing gives me something I can control and a strategy that actually works. It grounds me, keeps me present, and helps me get through the scan.
I know facing a PET scan can feel overwhelming, confusing, or even a little scary. I hope this guide helps you feel a bit more prepared and a little less alone. From one person navigating this process to another, I truly wish you strength, calm, and clarity. You are not alone, and you are stronger than you realise.
