This page is about your white blood cell scan at Royal Brompton Hospital. It tells you about the scan, what will happen at your appointment and what to expect on the day. 

A white blood cell scanhelps us find areas of inflammation or infection inside the body. It can show the location and extent of a problem when other tests cannot give clear answers.

A white blood cell scan is a longer procedure than many other scans. Some people will need to have scans on two consecutive days. We will talk to you about whether you need to come in for a second day at your appointment. 

This page explains what will happen, how to prepare, and what to expect on each day. Our team will support you throughout your visit.

What the scan involves

White blood cells are part of your body’s defence system. They naturally travel to areas where there is inflammation or infection.

For a white blood cell scan:

• A small sample of your blood is taken.
• Your white blood cells are separated from the sample.
• These cells are mixed with a small amount of radioactive tracer.
• The tracer attaches to your white cells (this is called “labelling”).
• Your labelled white cells are then injected back into your bloodstream.
• A gamma camera takes pictures as the cells move around your body.

The tracer does not cause any side effects.

The procedure is carried out over two consecutive days. On day 1, the procedure will take most of the day, and you need to be available all day. On day 2 you would need to be available for 1 hour. 

What will happen on day 1

When you arrive

• A technologist will explain the procedure and answer any questions.
• A blood sample of around 50 ml will be taken.
• Your white cells will be labelled in a specialist laboratory. This can take up to 4 hours.
• You may leave the department during this time.

Re‑injection and scans

• Once your cells are ready, they will be injected back into a vein in your arm or hand.
• You will then have two scans:
  • 1 hour after the injection
  • 4 hours after the injection
• Each scan takes around 15 minutes. During these scans an experienced technologist uses a gamma camara to take 3D images of your upper body. 
• You will need to lie still, but you can breathe normally.
• The scanner is similar in size to a CT scanner and quieter than an MRI scanner.

Clothing

• If your clothing has metal fastenings that cannot be removed, we may ask you to change into a gown.

Deciding whether you need to come back the next day

• You may be asked to return the next day for a final scan. This will be for delayed pictures. We will talk to you about whether you need to come back at your appointment. 

What will happen on day 2

• You will not need to have another injection for this scan. 
• This scan also takes around 15 minutes.

How to prepare

• No special preparation is needed for this scan.
• You can eat and drink normally before your appointment.
• You can continue taking your usual medicines unless your doctor has advised otherwise.
• Drink plenty of fluids before and after the injection to help clear any excess tracer.

Risks of radiation during a white blood cell scan

The amount of radiation used during a white blood cell scan is small and kept to a minimum. We believe that the benefits of having the scan far outweigh any risks.

The risk of a person getting cancer because of this radiation is low, 1 in 10,000 to 1 in 1,000 people. This level of risk is very small compared with the overall lifetime chance of getting cancer. The overall lifetime chance of getting cancer is around 1 in 2 people. 

After the scan

• A doctor will check the images while you wait.
• Once the images are confirmed, you can go home.
• The radiation dose from this scan is very small.
• You do not need to change your routine, but you should keep a small distance (around 2 meters) from children under 2 years of age for 24 hours. 
• The tracer will not make you sleepy.
• You can drive and return to normal activities. 

Your results

A nuclear medicine consultant will review your scan and send the report to your referring specialist. The results will also be available on the hospital’s electronic system.

Your specialist doctor will discuss the results with you and explain any next steps.