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What To Expect During a Lung Ventilation/Perfusion Scan

Lung ventilation/perfusion (VQ) scans are done at radiology clinics or hospitals.

For the test, you lie on a table for about 1 hour and have two types of scans: ventilation and perfusion. The ventilation scan shows the pattern of air flow in your lungs. The perfusion scan shows the pattern of blood flow in your lungs.

You must lie very still during the tests or the pictures may blur. If you're having trouble staying still, your doctor may give you medicine to help you relax.

Both scans use radioisotopes (a low-risk radioactive substance). This substance releases energy inside your body. Special scanners outside of your body use the energy to create images of air and blood flow in your lungs.

The radioisotopes used in VQ scans can cause an allergic reaction, including itching and hives. Medicines can relieve these symptoms.


For this scan, you lie on a table that moves under the arm of the scanner. You wear a breathing mask over your nose and mouth and inhale a small amount of radioisotope gas mixed with oxygen.

As you breathe, the scanner takes pictures that show air going into your lungs. You'll need to hold your breath for a few seconds at the start of each picture.

The scan is painless, and each picture takes only a few minutes. However, wearing the mask can make some people feel anxious. If this happens, your doctor may give you medicine to help you relax.


For this scan, a small amount of radioisotope is injected into a vein in your arm. The scanner then takes pictures of blood flow through your lungs.

The scan itself doesn't hurt, but you may feel some discomfort from the radioisotope injection.

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Lung Ventilation/Perfusion Scan Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Lung Ventilation/Perfusion Scan, visit

July 25, 2014 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.