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A lung scan is a type of nuclear scanning test. It is most often used to find a pulmonary embolism. This is a blood clot that prevents normal blood flow in the lung.
Two types of lung scans are usually done together:
If the lungs are working as they should, the results of the two scans will match. If the scan results don't match, you may have a blood clot in the lung.
Ventilation and perfusion scans can be done on their own or together. If both scans are done, the test is called a V/Q scan. The ventilation scan usually is done first.
A lung scan is done to:
Before your lung scan, tell your doctor if:
A chest X-ray is usually done the same day, either before or after the lung scan.
You may be asked to sign a consent form.
Talk to your doctor if you have any concerns about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
You will need to take off any jewelry that might interfere with the scan. You may need to take off all or most of your clothes, depending on which area is being examined. You will be given a cloth or paper covering to use during the test.
During the scan, you might lie on your back with the scanning camera over or under your chest. Or you might sit with the camera next to your chest. The camera does not produce any radiation.
For the ventilation scan, a mask will be placed over your mouth and nose. Or you may have a nose clip on your nose and a tube in your mouth that you use for breathing. You will take a deep breath and hold it.
The camera will take pictures as the tracer moves through your lungs.
You may be asked to breathe the gas in and out through your mouth for several minutes. You may then be asked to hold your breath for short periods (about 10 seconds) and to change positions. This is done so your lungs can be viewed from other angles. The camera may move to take pictures from different angles. You need to stay very still during the scans to avoid blurring the pictures.
Afterward, the radioactive gas or mist will clear from your lungs as you breathe.
The ventilation scan takes about 15 to 30 minutes.
For the perfusion scan, a small amount of the radioactive tracer is injected into your arm.
After the tracer is injected, the camera will take pictures as the tracer moves through your lungs. The camera may be repositioned around your chest to get different views. You need to stay very still during the scans to avoid blurring the pictures.
The perfusion scan takes about 5 to 10 minutes.
Breathing through the mask during the ventilation scan may be uncomfortable, especially if you feel very short of breath. But you will be given plenty of oxygen through the mask.
If you have a perfusion scan, you may feel nothing at all from the needle, or you may feel a brief sting or pinch. Otherwise, a lung scan is usually painless.
You may find it hard to stay still. Ask for a pillow or blanket to make yourself as comfortable as possible before the scan begins.
to the radioactive tracer are very rare. Most of the tracer will leave your body through your urine or stool within a day. So be sure to promptly flush the toilet and thoroughly wash your hands with soap and water. The amount of radiation is so small that it is not a risk for people to come in contact with you after the test.
Some people have soreness or swelling at the injection site. A moist, warm compress applied to the arm may help.
There is always a slight risk of damage to cells or tissue from being exposed to any radiation, even the low level of radiation released by the radioactive tracer used for this test. But the chance of damage is usually very low compared with the benefits of the test.
The results of a lung scan are usually ready in 1 day.
The radioactive tracer is evenly distributed throughout the lungs during ventilation and perfusion.
The ventilation scan is abnormal, but the perfusion scan is normal. This may mean abnormal airways in all or parts of the lung. It may be a sign of chronic obstructive pulmonary disease (COPD) or asthma.
The perfusion scan is abnormal, but the ventilation scan is normal. Depending on the difference between the two scans, it may be a sign of a pulmonary embolism.
Both the ventilation and perfusion scans are abnormal. This can be caused by certain types of lung disease, such as pneumonia or COPD, or by a pulmonary embolism.
Lung scan results can help your doctor find out how likely it is that you have a blood clot in your lung (pulmonary embolism). The results are most often reported in one the following ways:
You may not be able to have the test, or the results may not be helpful, if:
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
ByHealthwise StaffPrimary Medical ReviewerAnne C. Poinier, MD - Internal MedicineAdam Husney, MD - Family MedicineE. Gregory Thompson, MD - Internal MedicineMartin J. Gabica, MD - Family MedicineMyo Min Han, MD - Nuclear Medicine
Current as ofOctober 9, 2017
Current as of:
October 9, 2017
Anne C. Poinier, MD - Internal Medicine
& Adam Husney, MD - Family Medicine & E. Gregory Thompson, MD - Internal Medicine & Martin J. Gabica, MD - Family Medicine & Myo Min Han, MD - Nuclear Medicine
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