Summary
BackgroundThe main purpose of ventilation scanning, as adjunct to perfusion lung scintigraphy,
in acute pulmonary embolism is to allow for the classification of segmental perfusion
defects as mismatched, which is generally accepted as proof for the presence of pulmonary
embolism. We examined whether this function of the ventilation scan could be replaced
by the chest X-ray.MethodsIn 389 consecutive patients with suspected pulmonary embolism and at least one segmental
perfusion defect we classified the ventilation/perfusion (V/Q) scan and chest X-ray/perfusion
(X/Q) scan as either mismatched or matched. Furthermore we analyzed whether this comparison
was different in subgroups of patients with concomitant congestive heart failure or
chronic obstructive pulmonary disease.Results Overall agreement between the X/Q and V/Q scan diagnostic category was found in 341
of 389 patients (88%; 95% CI 84-92%). The positive predictive value for obtaining
a mismatched V/Q scan result in case of a mismatched X/Q scan result was 86% (95%
CI 81-90%). If the X/Q scan yielded only matched defects the V/Q scan resulted in
the same classification in 90% (95% CI 85-95%). Analysis of the small subgroup of
patients with chronic obstructive pulmonary disease showed that a mismatched X/Q scan
was confirmed by V/Q scanning in 21 of 34 cases (62%; 95% CI 45-78%).ConclusionThis study shows that in the great majority of patients with clinically suspected
acute pulmonary embolism combination of chest X-ray with perfusion scintigraphy reliably
replaced ventilation/perfusion scintigraphy in defining (mis)-matching of segmental
perfusion defects. These results need confirmation before the chest X-ray can fully
obviate the use of ventilation scintigraphy.
Key words
Chest X-ray - ventilation/perfusion scan - pulmonary embolism
