Ventilation perfusion isotope lung scans

Ventilation perfusion isotope (V/Q) lung scan is commonly used for investigating suspected chronic thromboembolic pulmonary hypertension. It is also used for investigating acute pulmonary embolism.

In acute pulmonary embolism, computed tomography pulmonary angiography (CTPA) is often preferred, but a V/Q lung scan may be chosen in some circumstances. The effective radiation dose for a V/Q lung scan is lower (2 to 3 mSv) than CTPA, which is useful particularly in younger female patients; see Radiation exposure in thoracic imaging for more information.

V/Q lung scan is also useful for patients who have a severe reaction to contrast media that precludes CTPA.

V/Q lung scans may be less useful than CTPA in patients with obstructive lung disease because the inhalational delivery of radiotracer to the lung can be impaired.