Interpretation of Ventilation-Perfusion Lung Scans

Scan Interpretation                            Frequency of Pulmonary Embolism Indicated Course   
High Probability
Two or more near-segmental or larger perfusion defects without matching ventilation defects
86-88%  Anticoagulation 
In determinant
Not fitting into other categories
21-33% Pulmonary Arteriogram
Low Probability    
a.  Subsegmental perfusion defects
b.  Single moderate perfusion defects
c.  Matched ventilation-perfusion defects
d.  Perfusion defects associated with  roentgenographic infiltrates                          
16-40% a. If clinical suspicion of pulmonary embolism is low, no further testing.
b. If clinical suspicion of roentgenographic infiltrates pulmonary embolism is high, pulmonary arteriogram
Normal/Near-normal Perfusion 0-4% No further testing