Effect of ventilation images on observer interpretation of lung perfusion examinations.

Independent, random, and multiple evaluations by three observers of pulmonary perfusion scintiscans with and without ventilation scans demonstrated a 39% reduction in diagnosis of pulmonary embolism when ventilation scans were included. These findings suggest that four of 10 cases diagnosed as having pulmonary emboli on the basis of perfusion imaging procedures alone would have the diagnosis changed.