You may need a lung ventilation/perfusion (VQ) scan if you have signs or symptoms of a pulmonary embolism (PE). A PE is a sudden blockage in a lung artery. A blood clot usually causes the blockage.
Some blood clots that can cause a PE travel to the lungs from veins deep in the legs. This can cause pain and swelling in the affected limb.
Doctors use VQ scans to help find out whether a PE is causing these signs and symptoms. A VQ scan alone, however, won't confirm whether you have a PE. Your doctor also will consider other factors when making a diagnosis.
Doctors also use VQ scans to detect poor blood flow in the lungs' blood vessels and to examine the lungs before some types of surgery.
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