Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is top normal . Mediastinal and hilar contours are unchanged with tortuosity of the thoracic aorta again noted . Low lung volumes cause mild crowding of the bronchovascular structures , though no overt pulmonary edema is seen . Patchy bibasilar airspace opacities most likely reflect atelectasis but infection is not completely excluded . No pleural effusion or pneumothorax is clearly noted . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes with patchy bibasilar opacities likely reflective of atelectasis . Infection however is not completely excluded .