Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a subtle linear right lower lung opacity , which likely corresponds to opacity seen on subsequent CT . This may represent a small focus of atelectasis , aspiration or pneumonia . No pleural effusion or pneumothorax is seen . Heart and mediastinal contours are within normal limits .
    OUTPUT:
    
Subtle linear right lower lung opacity , which likely represents atelectasis . Differential diagnosis includes early pneumonia and aspiration . Atelectasis is non-specific , but if this finding does not resolve , then acute pulmonary embolism should be a consideration . These findings were discussed with Dr . ___ by Dr . ___ by telephone at 9 : 15 a .m . on ___ .