Ventilation & Perfusion (VQ)

This study examines the air and blood flow into the patient’s lungs and is primarily used to diagnose blood clots in the lungs.

  • No preparation for the scan is required. Previous chest x-rays to be provided if possible.
  • The patient will be asked to breath in a radioactive gas through a tube to demonstrate the air supply to the lungs. This takes about 7 minutes. 
  • The patient will then be scanned, lying on a bed with the gamma camera moving around them.
  • Images will then be taken at different angles around the patient's chest. This takes about 15 minutes. 
  • The patient will then be injected with a radio-pharmaceutical to demonstrate the blood supply to your lungs. 
  • The images will be repeated and take about 10 minutes each.
  • A mismatch between the two sets of images helps in the diagnosis of pulmonary embolism (blood clots in the lungs).


Used to diagnose:

Shortness of breath Chest pain Suspected pulmonary embolism (blood clots) Chronic obstructive airways disease

Symptom or Suspected Disease

Shortness of breath Chest pain Pulmonary emboli - blood clots suspected Pulmonary complications of AIDS Lung ventilation & perfusion Lung transplant rejection Inhalation injury in burn patients Chronic obstructive airways disease

How to book

Patients will need to be referred to Nuclear Med by a referring doctor. Patients must select the specific scan/study required by their referring doctor and book an appointment at the most convenient location.


  • Medical aid authorisation (referring doctor to provide patient with specific ICD 10 code for medical aid authorisation)
  • Referring doctor’s name and practice number
  • Newly diagnosed oncology patients may need to register for oncology (referring doctor to facilitate registration)