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Noteworthy Publications

Scans used to diagnose lung cancer may not be accurate in areas with infectious lung disease


PET and CT scans are often combined as an aid to diagnosing lung cancer. A VA study suggests the method may produce more false-positives in regions of the country where certain infectious lung diseases are common.
PET and CT scans are often combined as an aid to diagnosing lung cancer. A VA study suggests the method may produce more false-positives in regions of the country where certain infectious lung diseases are common. (Photo: National Library of Medicine)

PET and CT scans are often combined as an aid to diagnosing lung cancer. A VA study suggests the method may produce more false-positives in regions of the country where certain infectious lung diseases are common. (Photo: National Library of Medicine)

Positron emission tomography (PET) is a medical imaging technique that produces 3-D images showing differences between healthy and diseased tissue. PET commonly used a radioactive tracer called FDG (fluorodeoxyglucose), so the test is sometimes called an FDG-PET scan.

FDG-PET scans are often used in combination with computed tomography (CT) scans to diagnose lung cancer. A team from VA's Tennessee Valley Health Care System and Vanderbilt University Medical Center in Nashville found that FDG-PET scans combined with CT are not as good at detecting lung cancer in regions where there is endemic infectious lung disease, compared with regions where such disease is not widespread.

The researchers reviewed 70 previous studies on FDG-PET. In patients who had pulmonary nodules but not lung cancer, FDG-PET was 16 percent more likely to give a false-positive result when the patients lived in regions where infectious lung disease is prevalent. This suggests that the lung diseases common in those regions may sometimes be mistaken for cancer on imaging tests.

Examples of regional lung diseases include histoplasmosis and blastomycosis, which are caused by inhaling airborne fungal spores. Tuberculosis is also much more common in some regions of the United States than in others. (Journal of the American Medical Association, Sept. 24, 2014)


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