The most definitive method of diagnosing pulmonary embolism is
Pulmonary ateriography
Radioisotope perfusion pulmonary scintigraphy
EKG
Venography
Pulmonary aeriography is the most definitive method of diagnosing pulmonary embolism.Chest CT with contrast has viually replaced invasive pulmonary angiography as a diagnostic test.A definitive diagnosis of PE depends on visualisation of an intraluminal filling defect in more than one projection.Secondary signs of PE include abrupt occlusion("cut-off") of vessels,segmental oligemia or avascularity,a prolonged aerial phase with slow filling,and touous,tapering peripheral vessels. Reference:Harrison's medicine-18th edition,page no:2174.
Respiratory system