How the I123 MIBG cardiac scan works

Nuclear medicine scans usually involve being injected with a very small amount of a radioactive substance - what we call, a tracer or radiotracer. This particular tracer is called I123 MIBG and is used to collect in certain areas of the heart muscle. While there the tracer gives off gamma rays which are then picked up by a special camera which allows us to diagnose what the issue may be. 

What to expect from the scan

If you think you might be pregnant, or if you are currently breastfeeding please let the technologist know when you arrive. 

If everything is okay when you arrive in the nuclear medicine department, you'll be asked to drink a small cup of water with potassium iodine added -  this may have a slight metallic taste. After an hour, the technologist will then insert a small tube - called an intravenous line (IV) - into a small vein and inject a small amount of radioactive I123 MIBG tracer into it. You'll be asked to stay in the nuclear medicine department for 30 minutes while we monitor you and take the first scan of your heart. You'll then get a break of three hours. You may leave the area during this time, but do not do any strenuous activities or exercise.

After three hours and 50 minutes, we'll ask you to lie on the exam table for a second scan - the technologists will help to make you comfortable. It's sometimes difficult but we'll ask you to try to lie as still as you can while the camera is taking pictures. If you move, the pictures will be blurry and may have to be taken again.

The camera will take still photos and 3D images called SPECT (single photon emission computed tomography). During the SPECT scan, the camera will rotate around your body. A low-dose computed tomography (LDCT) scan may be done at the same time as the SPECT scan.

The imaging session may take up to 60 minutes.

After the procedure

After your scan, try to drink plenty of water, this helps your body to get rid of the tracer. Most of it will leave your body in your urine or stools, and the rest will go away over time. After your scan, you should be able to restart any medicines you were advised to stop taking before the scan. 

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

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