This scan assesses blood supply (Q) and aeration (V) to your lungs. The combination of V and Q helps us understand the function of your lungs.

How does it work?

V (ventilation scan)

This is performed on a scanner bed while you breathe room air mixed with minimally radioactive, tasteless and odourless 82mkrypton gas. This shows the aeration to your lungs. You will breathe normally through a face mask for up to 10 minutes.

Q (perfusion scan)

You will receive a small dose of radioactive material called 99mTc-MAA that reaches the smallest network of blood vessels in the lungs. For this, you will need to lie on a flatbed for a tracer injection while breathing deeply.  After five minutes, you will have a 3D (SPECT – single photon emission computed tomography) scan, which can take up to 20 minutes.

Low-dose computed tomography scan (LDCT)

We may perform a very low-dose computed tomography (LDCT) scan, similar to an X-ray, to see the structure of your chest. This may take up to five minutes.

An experienced technologist will perform the scans by rotating a gamma camera slowly around your chest. This allows us to see your lungs in 3D. You will need to lie still for all three scans. When these are all completed, the results are used together to get detailed information of your lung function.

How should I prepare?

There is no preparation required for this test.

You will need to keep your arms raised above your shoulders to allow the camera get as close to your chest as possible. If you are unable to keep your arms raised above your shoulders, we may have to perform a less detailed planar imaging of your lungs.

After the procedure

Once the scan has finished, the doctor will check the quality of your scan while you wait. Once checked, 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.

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

Department head

Kshama Wechalekar