Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . Lung volumes are low . There is no pleural effusion or pneumothorax . The lateral view shows vague focal opacification projecting over the lower spine ; no correlate is seen on the frontal view .
    OUTPUT:
    
Vague posterior lower lobe opacity , not very characteristic of pneumonia , although infectious process is possible . Instead main concern is to exclude a nodule ; this could be probably be accomplished by repeating the study with standard PA and lateral technique with optimal inspiration when clinically feasible since this may be due to minor atelectasis or summation artifact .