Pulmonary ventilation/perfusion scan
V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan; Pulmonary embolism - V/Q scan; PE- V/Q scan; Blood clot - V/Q scanA pulmonary ventilation/perfusion scan involves two nuclear scan tests to measure breathing (ventilation) and circulation (perfusion) in all areas of the lungs.
Nuclear scan
A positron emission tomography (PET) scan is a type of imaging test. It uses a radioactive substance called a tracer to look for disease in the body...
How the Test is Performed
A pulmonary ventilation/perfusion scan is actually 2 tests. They may be done separately or together.
During the perfusion scan, a health care provider injects radioactive albumin into your vein. You are placed on a movable table that is under the arm of a scanner. The machine scans your lungs as blood flows through them to find the location of the radioactive particles.
During the ventilation scan, you breathe in radioactive gas through a mask while you are sitting or lying on a table under the scanner arm.
How to Prepare for the Test
You do not need to stop eating (fast), be on a special diet, or take any medicines before the test.
A chest x-ray is usually done before, and sometimes after a ventilation and perfusion scan.
Chest x-ray
A chest x-ray is an x-ray of the chest, lungs, heart, large arteries, ribs, and diaphragm.
You wear a hospital gown or comfortable clothing that does not have metal fasteners.
How the Test will Feel
The table may feel hard or cold. You may feel a sharp prick when the IV is placed in the vein in your arm for the perfusion part of the scan.
The mask used during the ventilation scan may make you feel nervous about being in a small space (claustrophobia). You must lie still during the scan.
The radioisotope injection usually does not cause discomfort.
Radioisotope
A positron emission tomography (PET) scan is a type of imaging test. It uses a radioactive substance called a tracer to look for disease in the body...
Why the Test is Performed
The ventilation scan is used to see how well air moves and blood flows through the lungs. The perfusion scan measures the blood supply through the lungs.
A ventilation and perfusion scan is most often done to detect an acute pulmonary embolus (blood clot in the lungs). It is also used to:
Pulmonary embolus
A pulmonary embolus is a blockage of an artery in the lungs. The most common cause of the blockage is a blood clot.
- Detect abnormal circulation (shunts) in the blood vessels of the lungs (pulmonary vessels)
- Detect abnormal circulation from multiple old blood clots (chronic thromboembolic disease)
- Test regional (different lung areas) lung function in people with advanced pulmonary disease, such as COPD
Pulmonary disease
Lung disease is any problem in the lungs that prevents the lungs from working properly. There are three main types of lung disease:Airway diseases -...
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Chronic obstructive pulmonary disease (COPD) is a common lung disease. Having COPD makes it hard to breathe. There are two main forms of COPD:Chroni...
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Normal Results
The provider should take a ventilation and perfusion scan and then evaluate it with a chest x-ray. All parts of both lungs should take up the radioisotope evenly.
What Abnormal Results Mean
If the lungs take up lower than normal amounts of radioisotope during a ventilation or perfusion scan, it may be due to any of the following:
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Airway obstruction
Airway obstruction
Blockage of the upper airway occurs when the upper breathing passages become narrowed or blocked, making it hard to breathe. Areas in the upper airw...
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Pneumonia
Pneumonia
Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung. This article covers community-acquired pneumonia (CAP). ...
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- Pneumonitis (inflammation of the lungs due to breathing in a foreign substance)
- Pulmonary embolus
- Chronic thromboembolic pulmonary disease
- Reduced breathing and ventilation ability
Risks
Risks are about the same as for x-rays (radiation) and needle pricks.
No radiation is released from the scanner. Instead, it detects radiation and converts it into an image.
There is a small exposure to radiation from the radioisotope. The radioisotopes used during scans are short-lived. All of the radiation leaves the body in a few days. However, as with any radiation exposure, caution is advised for pregnant or breastfeeding women.
There is a slight risk for infection or bleeding at the site where the needle is inserted. The risk with perfusion scan is the same as with inserting an intravenous needle for any other purpose.
Intravenous
Intravenous means "within a vein. " Most often it refers to giving medicines or fluids through a needle or tube inserted into a vein. This allows th...
In rare cases, a person may develop an allergy to the radioisotope. This may include a serious anaphylactic reaction.
Allergy
An allergy is an immune response or reaction to substances that are usually not harmful.
Anaphylactic reaction
Anaphylaxis is a life-threatening type of allergic reaction.
Considerations
A pulmonary ventilation and perfusion scan may be a lower-risk alternative to pulmonary angiography for evaluating disorders of the lung blood supply.
Pulmonary angiography
Pulmonary angiography is a test to see how blood flows through the lung. Angiography is an imaging test that uses x-rays and a special dye to see th...
This test may not provide a definite diagnosis, particularly in people with lung disease. Other tests may be needed to confirm or rule out the findings of a pulmonary ventilation and perfusion scan.
This test has largely been replaced by CT pulmonary angiography for diagnosing pulmonary embolism. However, people with kidney problems or an allergy to contrast dye can more safely have this test.
References
Goldhaber SZ, Piazza G. Pulmonary embolism and deep vein thrombosis. In: Libby P, Bonow RO, Mann, DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 87.
Herring W. Nuclear medicine: understanding the principles and recognizing the basics. In: Herring W, ed. Learning Radiology: Recognizing the Basics. 4th ed. Philadelphia, PA: Elsevier; 2020:e24-e42.
Murphy JA, Safi F. Ventilation-perfusion scan. In: Hughes G, ed. A Medication Guide to Internal Medicine Tests and Procedures. Philadelphia, PA: Elsevier; 2022:chap 60.
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Albumin injection - illustration
Radioactive albumin injection is part of a nuclear scan test that is performed to measure the supply of blood through the lungs. After the injection, the lungs are scanned to detect the location of the radioactive particles as blood flows through the lungs.
Albumin injection
illustration
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Albumin injection - illustration
Radioactive albumin injection is part of a nuclear scan test that is performed to measure the supply of blood through the lungs. After the injection, the lungs are scanned to detect the location of the radioactive particles as blood flows through the lungs.
Albumin injection
illustration
Review Date: 7/31/2022
Reviewed By: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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