Lung Scan

Test Overview

A lung scan is a type of nuclear scanning test. It is most often used to find a pulmonary embolism. This is a blood clot that prevents normal blood flow in the lung.

Two types of lung scans are usually done together. They are:

Ventilation scan.

You inhale a radioactive tracer gas or mist. Pictures from this scan can show areas of the lungs that aren't getting enough air or that hold too much air.

Perfusion scan.

A radioactive tracer is injected into a vein in your arm. It travels through your blood and into the lungs. Pictures from this scan can show areas of the lungs that aren't getting enough blood.

If the lungs are working as they should, the results of the two scans will match. If the scan results don't match, you may have a blood clot in the lung.

Ventilation and perfusion scans can be done on their own or together. If both scans are done, the test is called a V/Q scan. The ventilation scan usually is done first.