Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are seen causing crowding of the bronchovascular structures . Seen on lateral view in the retrocardiac region is increased opacity not clearly localized on the frontal view . The heart is top - normal in size , and no pleural effusion or overt pulmonary edema is seen . The mediastinal contours are normal .
    OUTPUT:
    
Low lung volumes . Left basilar opacity best seen on lateral view may be due to atelectasis although infection can not be excluded .