Radionuclide lung scanning is used to diagnose pulmonary embolism. It involves two scans that are performed simultaneously: one to assess blood flow through the lungs and the other, which is called a ventilation scan, to assess airflow. A diagnosis can be made by comparing the ventilation scan and the blood flow scan because many lung disorders disrupt the flow of both blood and air in a specific area, whereas a pulmonary embolism disrupts only blood flow. The procedure usually takes about 20 minutes to perform.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.