The predictability of matched ventilation perfusion scan in pulmonary embolism.

: In retrospect, we reviewed 17 cases of proven pulmonary emboli at Taichung VGH. These patients were then divided into two groups, the matched and the mismatched V/Q scan. Patients with lung consolidation, along with their chest films, were studied and characterized. In the matched V/Q group (5 cases), perfusion defects were comparable with lung consolidation in both size and location. In the V/Q mismatched group, perfusion defects were larger than lung consolidation (either single or multiple foci). A matched V/Q scan in patients with a pulmonary embolism, may result from lung consolidation induced by a pulmonary infarction, localized edema, or hemorrhage. A matched V/Q scan with localized lung consolidation in a suspicious case could not rule out pulmonary embolism, and further evaluation is mandatory.