V/Q Scan
Reviewed
Also called: Ventilation/perfusion scan, Pulmonary ventilation/perfusion scan, Lung scan, Lung V/Q scan, Lung scintigraphy
A V/Q scan consists of two imaging tests that look for certain lung problems. A ventilation scan measures how air moves in and out of your lungs. A perfusion scan measures circulation (how blood flows in the lungs). The scans help diagnose different lung conditions, but 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
- To test lung function in people with certain lung diseases, such as COPD
Preparation and collection
A chest x-ray is usually done before a V/Q scan.
You will lie very still on a special table while the scanner takes pictures of your lungs or sit in a chair in front of a special camera. For a ventilation scan, you will wear a face mask and breathe in a harmless gas that contains the radioactive tracer. For a perfusion scan, the tracer is injected into your vein through an IV line. Each test takes about 15 minutes; if both tests are done, it takes about 30 to 60 minutes.
There is very little exposure to radiation in a V/Q scan. Only a small amount of radioactive substance is used, and all the radiation leaves your body within a few days. While radiation exposure in a V/Q scan is safe for most adults, it can be harmful to a developing baby. 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. You may have a little discomfort when the tracer is injected during a perfusion scan. Allergic reactions to the tracer are rare and usually mild.
Understanding results
Results should be interpreted by your healthcare provider. The following patterns are based on the source.
- Normal ventilation and perfusion scans: No evidence of a pulmonary embolism or other major lung problem. Limitation: A normal scan does not rule out all lung conditions. Next step: Routine
- Mismatch between ventilation and perfusion images: Areas of the lung that have normal airflow but reduced blood flow may indicate a pulmonary embolism (PE). Limitation: Other conditions can also cause mismatches; the scan is most often used to check for PE. Next step: If a PE is suspected, you will need medical treatment right away.
- Abnormal ventilation and/or perfusion scans (other patterns): May indicate conditions such as COPD, pneumonia, or heart failure. Limitation: Further evaluation is needed to confirm the specific condition. Next step: Prompt
- The scan uses a small amount of radioactive tracer; radiation exposure is very low and leaves the body within a few days.
- The tracer may be harmful to a developing baby; tell your provider if you are pregnant or think you may be pregnant.
- The tracer may contaminate breast milk; tell your provider if you are breastfeeding.
- Allergic reactions to the tracer are rare and usually mild.
- Results should be interpreted by your healthcare provider; the source does not provide specific reference intervals or units.
What to do next
If you have questions about your results, talk to your provider. If diagnosed with a pulmonary embolism, treatment may include blood thinners, clot busters, or surgical procedures.
- What do my specific V/Q scan results mean for my health?
- Do I need any follow-up tests or treatments based on these results?
- Are there any precautions I should take regarding the radioactive tracer?