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Lung Scan

What To Think About

  • Checking for a blood clot in your leg (deep venous thrombosis) can help your doctor decide if you are at high risk for having a pulmonary embolism. After a medical history and physical examination are done to establish your risk level (pretest probability) for deep leg vein thrombosis, an ultrasound is usually done. Your pretest probability and initial ultrasound results will help your doctor determine the most appropriate follow-up tests to see whether you have a pulmonary embolism. To learn more, see the topic Doppler Ultrasound.
  • Uncertain perfusion scan results are sometimes investigated further using pulmonary angiography or a newer computed tomography scanning technique called CT pulmonary angiography, or CTPA. Pulmonary angiography is an X-ray test that uses contrast material injected into the bloodstream to evaluate the blood flow through the arteries leading to the lungs (pulmonary arteries). Many medical centers or doctors now use CTPA as their first choice for evaluating a pulmonary embolus rather than a lung scan because CT has become more available.
  • Lung scan results for people who have a long-term (chronic) lung disease, such as emphysema or chronic obstructive pulmonary disease (COPD), may be hard to interpret. For this reason, other tests, such as CT angiogram, may be done.
  • The results of a combined (ventilation and perfusion) lung scan, often called a V/Q scan, may be hard to interpret. These results should be interpreted along with a person's symptoms and the results of other tests, such as a physical exam, lab tests, and a chest X-ray.

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 Staff
Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine
Specialist Medical ReviewerMyo Min Han, MD - Nuclear Medicine
Last RevisedOctober 1, 2012

WebMD Medical Reference from Healthwise

Last Updated: October 01, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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