Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . Hilar and mediastinal contours are normal . Subtle retrocardiac opacity is likely secondary to atelectasis . No other consolidations concerning for infection are identified . There is no pleural effusion or pneumothorax . The visualized osseous structures are unremarkable .
    OUTPUT:
    
Subtle retrocardiac opacity is likely secondary to atelectasis . No other consolidations concerning for infection is identified .