Medical Content Created by the Faculty of the
Harvard Medical School
The test is performed in the radiology department of a hospital or in an outpatient facility. You are asked to put on a hospital gown. Once you are ready, multiple pictures of your chest are taken from different angles, using a special camera that detects the radionuclide. For half of these pictures, you are asked to breathe from a tube that has a mixture of air, oxygen, and a slightly radioactive version of a gas called xenon, which can be detected by the camera, and which measures airflow in different parts of the lung. For the other half of the pictures, the camera tracks the injected radionuclide to determine blood flow in different parts of the lung. A blood clot is suspected in areas of the lung that have good airflow but poor blood flow. Except for the minor discomfort of having the IV placed, the test is painless. It usually takes less than one hour.