V/Q Scan
Reviewed
Also called: Ventilation/perfusion scan, Lung V/Q scan, Lung scintigraphy
A V/Q scan consists of two imaging tests that look for certain lung problems. They are most often used to check for a pulmonary embolism (PE).
Specimen: Not applicable (imaging study)
Why this test may be ordered
- To check for a pulmonary embolism (PE)
- To find problems with blood flow in the lungs
- To check lung function before lung surgery or in lung diseases such as COPD
Preparation and collection
A chest x-ray is usually done before a V/Q scan.
V/Q scans are usually performed in a radiology clinic or a hospital. Before the scan, you will be given a substance called a radioactive tracer. Each test takes about 15 minutes, so if you have both tests, it will take about 30 to 60 minutes.
There is very little exposure to radiation in a V/Q scan. So be sure to tell your provider if you are pregnant or think you may be pregnant. Also, tell your provider if you are breastfeeding, since the tracer may contaminate your breast milk. Allergic reactions to the tracer are rare and usually mild.
Understanding results
If a result or symptoms suggest an emergency, get emergency medical help right away.
If your ventilation and/or perfusion scan results were not normal, it may mean something is keeping your lungs from working properly.
- Ventilation and perfusion images don't match: If the pictures from the ventilation and perfusion scan don't match, it could mean you have a pulmonary embolism (PE) and will need medical treatment right away. Limitation: This is a serious condition and can be life-threatening. Next step: If you are diagnosed with a pulmonary embolism (PE), your treatment may include medicines such as blood thinners, which help prevent clots from forming, or clot busters, which help dissolve clots quickly.
- Other abnormal ventilation and/or perfusion results: If your ventilation and/or perfusion scan results were not normal, it may mean something is keeping your lungs from working properly. Limitation: The scans may also show that you have a different condition affecting your lungs. Next step: If you have questions about your results, talk to your provider.
- Radiation can be harmful to a developing baby, so a different test may be used in pregnancy.
- Abnormal results can also come from COPD, pneumonia, or heart failure.
- Many people with a PE don't have symptoms.
What to do next
If you have questions about your results, talk to your provider.
- Will I need both the ventilation and perfusion scans?
- What should I do if I am pregnant or breastfeeding?
- What happens next if the scans don't match?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.