Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . There is very minimal retrocardiac opacity seen on the PA view which is most likely due to the atelectasis . The lungs are otherwise clear . No pleural effusion or pneumothorax is seen .
    OUTPUT:
    
Minimal retrocardiac atelectasis .