Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Both of the lower lung volumes seen on the current exam . Retrocardiac opacity may be secondary to atelectasis . Elsewhere the lungs are grossly clear . The cardiomediastinal silhouette is within normal limits given low inspiratory effort . Degenerative changes noted at the acromioclavicular joints .
    OUTPUT:
    
Low lung volumes with left basilar opacity may be due to atelectasis noting that infection is not entirely excluded .