Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: On the lateral view , an opacification overlies the lower thoracic spine , but is difficult to localize on the frontal projection . Linear opacity near the left lung base likely represents atelectasis . There is a tiny right pleural effusion . Again noted is slight prominence of the central pulmonary arteries , which is unchanged from prior . The heart size is normal . Old right rib fractures are again noted .
    OUTPUT:
    
Opacity seen overlying the spine may represent pneumonia in the appropriate clinical setting . It is difficult to localize , as it is not conspicuous on the frontal view , but may be in the right lower lung as seen on previous radiographs .