Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Right Swan - Ganz catheter and endotracheal tube remain in standard position . Mediastinal drains and chest tubes have been removed . Focal crescent of lucency along the left mediastinal border may reflect tiny pneumothorax or pneumomediastinum . Slight improvement in the retrocardiac opacity can be improving atelectasis . Right basilar opacities slightly increased , has imaging appearance of atelectasis .
    OUTPUT:
    
Focal crescent of lucency along the left mediastinal border may reflect tiny pneumothorax or pneumomediastinum .