Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is mildly enlarged . The mediastinal and hilar contours are unchanged . Patchy opacities are noted in the lung bases , and not substantially changed from the previous exam . The pulmonary vasculature is normal . No pleural effusion or pneumothorax is present . There are no acute osseous abnormalities .
    OUTPUT:
    
Patchy bibasilar airspace opacities likely atelectasis .