Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable view of the chest . No prior . The lung volumes are seen . There is retrocardiac opacity , which silhouettes the hemidiaphragm , which could be due to atelectasis given low lung volumes , however , component of effusion or consolidation is also possible . Elsewhere , the lungs are grossly clear . Cardiac silhouette is within normal limits for technique and low inspiratory effort . Osseous and soft tissue structures are unremarkable . No free air below the diaphragm .
    OUTPUT:
    
Low lung volumes . Left basilar opacity silhouetting the hemidiaphragm , potentially due to atelectasis ; however , repeat exam with PA and lateral can be performed if the patient is amenable .