Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest demonstrate low lung volumes , which accentuate bronchovascular markings . Hilar and mediastinal silhouettes are unchanged . Heart size is normal . There is mild perihilar vascular congestion . Retrocardiac opacities are better seen on the lateral view projecting over spine . Right lung base opacities likely represent atelectasis . There is no pneumothorax . The partially imaged upper abdomen is unremarkable .
    OUTPUT:
    
Low lung volumes . Retrocardiac opacities , may represent atelectasis or infection in the appropriate clinical setting .