White blood cells are part of the body’s defence system. They help us to identify problems because they tend to collect in areas where tissue is infected or inflamed.

If we suspect that you have an internal area of inflammation or infection, a white cell scan is the easiest way to give us more information about what and where the condition might be located. 

Before your scan

You can eat and drink as normal before your first scan, and take all your usual medication as needed. We will, however, ask you to empty your bladder just before the scan. 

During your white cell scan

We'll take a sample of blood (50ml) from and extract the white cells from it. We then mix your white cells with with a small amount of radioactivity, known as a tracer, so the cells incorporate some of the radioactive material – this technique is called labelling. This process is performed in a specialist laboratory and may take up to four hours. These cells are then injected back into you, usually through a vein in your arm or hand, and allowed to circulate around your body before images are taken using a gamma camera.

There are two methods of labelling the white cells: with a tracer called technetium HMPAO or with another called indium oxine. The chosen method will depend on how long you have had the infection or where it is suspected to be located.

Depending on which method is chosen, we take pictures either one hour and four hours, or just four hours after the cells are injected. You may also be asked to attend the following day for further images. The schedule will be discussed with you at the time of appointment. 

An experienced technologist will perform the scans by making the gamma camera move slowly over you while you lie still on a scanning couch. This usually takes around 30 minutes. We may also perform a single-photon emission computed tomography (SPECT) scan, where the camera rotates slowly around the area we want to look at more closely and allows us to see your body in 3D. This will take around 45 minutes and you will need to lie still for the whole duration of the scan.

For the first scan, we'll ask you to be available for the whole day because that's often how long the procedure takes, you will only be needed for around an hour on the second day. 

After your scan

Once finished, the doctor will check the quality of your scan while you wait, and the technologist will then let you go home. The radiation dose from this procedure is very small and there is no need to make any changes to your routine.

We advise drinking plenty of fluid after the injection. This helps to flush any excess tracer from your body and also makes the images clearer. You may eat normally during this time.

There are no side effects from the injection; it will not make you feel sleepy or affect your ability to drive.

There are currently no related conditions associated with this test.

Royal Brompton nuclear medicine

Level 3, Chelsea Wing, Sydney Street


Monday to Friday, 9am to 5pm

Tel: 020 7351 8666 / 9
Fax: 020 7351 8668
Email: nmadvice@rbht.nhs.uk

Patient advice line: 020 7351 8667

If you have any questions or concerns about the scan please call our patient advice line.

It is an answerphone service – leave a message and we will call you back within 24 hours.

Department head

Kshama Wechalekar