How do I prepare for a VQ scan?
You don’t need to do anything specific to prepare for a VQ scan. You can eat and take medications as you normally would. Tell your provider:
- If you’re pregnant or think you might be. Your provider might suggest a different form of imaging to reduce the risk of radiation exposure to the fetus.
- If you’re breastfeeding/chestfeeding. Your provider might give you instructions on how to feed your baby on the day of the test or following the procedure. This reduces the risk of exposing your baby to radiation in your milk.
- If you don’t think you can sit or lay still for several minutes at a time. Movement can blur the images and your provider won’t be able to use them.
How long does a VQ scan take?
A VQ scan takes between 30 and 60 minutes. Each test takes about 15 minutes. Yours may take more or less time depending on prep time and whether your provider’s getting the images they need.
What happens before a VQ scan?
Before you get a VQ scan, you’ll get a chest X-ray. This can be anywhere from one to 24 hours before your scan. This gives your provider more information to help them understand the VQ scan results.
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What happens during this procedure?
A VQ scan has two parts: the ventilation test and the perfusion test. Some people will only do one, but most people will do the ventilation test followed immediately by the perfusion test in the same day. A provider will be there to guide you through both parts of the scan. They may ask you to change into a gown for the procedures.
Ventilation scan
During the scan:
- Your provider will help you put on a device that you’ll breathe from. This might be a mouthpiece (your provider will also put a clip over your nose to make sure you only breathe through your mouth) or a mask that fits closely over your mouth and nose.
- Your provider will attach the mouthpiece or mask to a machine with a hose. They’ll add the tracer to the hose.
- You’ll either lie on a table or sit in a chair to take pictures. If you’re lying on a table, it’ll slide into a machine that looks like a cylinder. If you’re in a chair, your provider will position you in front of the camera.
- You’ll breathe in through the mask or mouthpiece while the camera takes pictures.
- Your provider will reposition your body during the test to get the pictures they need.
- Your provider will have you take the mask off or mouthpiece out. They may take pictures for another minute or two after that.
Perfusion scan
In most cases, you’ll move to the perfusion scan immediately after the ventilation scan. The perfusion scan is very similar to the ventilation scan. Instead of breathing the radioactive tracer in through a mask or mouthpiece, your provider will inject the tracer into your vein using an IV.
What happens after a VQ scan?
After a VQ scan, the tracer will leave your lungs as you breathe in fresh air. The injected tracer will lose its radioactivity and leave the rest of your body through your pee and poop in a few hours or days. The provider who ordered the scan will let you know the results.
When will I know the results of my VQ scan?
You’ll usually know the results of a VQ scan within 24 hours.
What do the results of a VQ scan mean?
If the results of your VQ scan are abnormal, it means something is preventing your lungs from working properly. If the sets of pictures from the two parts of the scan don’t match, it could mean you have a pulmonary embolism (PE).
If your images show you have normal air and blood flow in your lungs, or that your chance of a blood clot is low, you might see one of these terms on your scan report:
- Normal.
- Low probability.
- PE absent.
- No evidence of PE.
If there’s a possibility that you have a blood clot, but it couldn’t be determined based on these images. You might need more tests if you see one of these terms on your scan report:
- Intermediate probability.
- Indeterminate probability.
- Nondiagnostic.
Based on the following scan results, you likely have a blood clot. Your provider will talk to you about your treatment options.
- High probability.
- PE present.
- PE-positive.
