Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size and cardiomediastinal contours are stable . Lung volumes are very low . Subtle retrocardiac opacity may be accentuated by patient rotation . The right lung is clear . No large pleural effusion or pneumothorax .
    OUTPUT:
    
Subtle retrocardiac opacity accentuated by patient rotation . Underlying infection or aspiration can not be excluded . PA and lateral radiographs may be helpful when the patient is able .