Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low , resulting in crowding of the hilar and mediastinal structures . Note is made of mild bibasilar atelectasis . There may be a small left pleural effusion . There is no evidence of pneumothorax . Note is made of tortuosity of the aorta . An intramedullary metallic rod is visualized within the right proximal humerus , with evidence of sclerosis within the humeral head .
    OUTPUT:
    
Low lung volumes . Possible small left pleural effusion .