Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . There is patchy posterior basilar opacity depicted on the lateral view . It is not certain to which side it may refer , but more likely the right lower lobe than left . There no pleural effusions or pneumothorax .
    OUTPUT:
    
Vague posterior basilar opacity , probably atelectasis ; etiologies such as aspiration and infectious bronchopneumonia are not excluded , however . Short - term follow - up radiographs may be appropriate to reassess .