Pulmonary ventilation/perfusion scan

Alternate Names : V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan

Normal Values

A ventilation and perfusion scan should be correlated with a chest X-ray. There should be uniform uptake of radioisotope in all portions of the lungs with equal distribution in both lungs.

What abnormal results mean

A decreased uptake of radioisotope during a perfusion scan indicates a problem with blood flow, including occlusion of the pulmonary arteries. A localized decreased in perfusion scan uptake (particularly when ventilation scan is normal) may indicate pulmonary embolus. Larger areas of decreased perfusion scan uptake may indicate a condition such as pneumonitis.

A decreased uptake of radioisotope during a ventilation scan may indicate reduced breathing and ventilation ability or airway obstruction. A decreased ventilation uptake (plus X-ray evidence of consolidation) may indicate pneumonia. Larger areas of poor uptake may indicate damage from chronic smoking or COPD.

Special considerations

A pulmonary ventilation and perfusion scan may be a lower-risk alternative to pulmonary angiography for some people to evaluate disorders of the lung blood supply.

This test may not provide an absolute diagnosis, particularly in people with underlying lung disease. Other tests may be necessary to confirm or rule out the findings of a pulmonary ventilation and perfusion scan.