A lung scan is an imaging test to look at your lungs and help diagnose certain lung problems. A lung scan may also be used to see how well treatment is working.
A lung scan is a type of nuclear imaging test. This means that a tiny amount of a radioactive matter is used during the scan. The radioactive matter called tracer sends out gamma rays. These rays are picked up by the scanner to make a picture of your lungs.
A lung scan can be a ventilation scan or a perfusion scan. A ventilation scan looks at how air moves in and out of your lungs. In particular, it looks at how air moves through the bronchi and bronchioles within your lungs. A perfusion scan looks at how blood is flowing within your lungs.
In a perfusion scan, the radioactive tracer is absorbed evenly where blood flow is normal. Areas that are not getting blood do not absorb the tracer. In a ventilation scan, the tracer will fill the lungs unless you have an area where the air cannot move.
The areas of the lungs where the radioactive tracer collects in greater amounts are called “hot spots.” The areas that do not absorb the tracer and appear less bright on the scan image are referred to as “cold spots.”
Lung scans are most often used to diagnose and find blood clots or other small masses called emboli in the lungs. But your healthcare provider may also use the scan to help diagnose other lung conditions.
You may need a lung scan if you have symptoms of a blood clot in your lung. Symptoms include:
If your healthcare provider thinks you may have a blood clot, you will have a ventilation scan and a perfusion scan. They will be done one right after the other. If the ventilation scan is normal, but the perfusion scan is not, it is called a mismatch. A mismatch often means that you have a blood clot.
You may also need a lung scan if your healthcare provider thinks you may have:
You may also have a lung scan before lung surgery. This is done to see how blood is flowing in your lungs and to see how well they are working.
Your healthcare provider may have other reasons to recommend a lung scan.
The risk from the radioactive tracer is very low. The amount used in the test is very small. You may feel some slight discomfort when the tracer is injected. Allergic reactions to the tracer are rare, but they may happen.
Lying on the scanning table during the procedure may cause some discomfort or pain for certain people.
Tell your healthcare provider if you:
You may have other risks that are unique to you. Let your healthcare provider know about all your medical conditions.
Make a list of questions you have about the procedure. Be sure to discuss these questions and any concerns with your healthcare provider prior to the procedure. Consider bringing a family member or trusted friend to the medical appointment to help you remember your questions and concerns.
Certain things can make a lung scan less accurate. These include:
You may have a lung scan as an outpatient or as part of your stay in a hospital. The way the test is done may vary depending on your condition and your healthcare provider’s practices.
You may have either a perfusion scan or a ventilation scan. Or you may have both scans. If you have both scans, one will be done right after the other.
Generally, a lung scan follows this process:
The lung scan is not painful. But you may have some discomfort or pain from lying still during the test. This may because of recent surgery or a joint injury. The technologist will use all possible comfort measures and do the scan as quickly as possible to minimize any discomfort or pain.
You may be watched for a short while after the test for any signs that mean you are allergic to the tracer.
You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness.
You may be told to drink plenty of fluids and empty your bladder often for 1 to 2 days after the scan. This will help flush the radioactive tracer from your body.
The medical staff will check the IV site for any signs of redness or swelling. Tell your healthcare provider if you see any pain, redness, or swelling at the IV site after you go home. These may be signs of infection or another type of reaction.
You should not have any other nuclear medicine tests for the next 24 to 48 hours after your lung scan.
You may go back to your usual diet and activities as directed by your healthcare provider.
Your healthcare provider may give you other instructions, depending on your situation.
Before you agree to the test or the procedure make sure you know: