Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: New retrocardiac opacities are seen on lateral view , corresponding to the left lower lobe , are likely due to atelectasis . Mild pulmonary congestion is noted . The heart size is normal . No pulmonary edema or pneumothorax .
    OUTPUT:
    
Retrocardiac opacities are likely atelectasis .