Ventilation-Perfusion Scan or "V-Q Scan"

What is the test?

The ventilation-perfusion scan is a nuclear scan so named because it studies both airflow (ventilation) and blood flow (perfusion) in the lungs. The initials V-Q are used in mathematical equations that calculate airflow and blood flow. The test is used primarily to help diagnose a blood clot in the lungs, called a pulmonary embolus.

Today, ventilation-perfusion scans are rarely performed because a chest CT scan is a much more accurate diagnostic test for detecting a pulmonary embolus.

How do I prepare for the test?

About one hour before the test, a technician places an IV in your arm. A slightly radioactive version of the mineral technetium mixed with liquid protein is injected through the IV to identify areas of the lung that have reduced blood flow.

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