Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes cause bibasilar linear atelectasis . There is no pleural effusion , pulmonary edema , or pneumothorax . The cardiomediastinal silhouette is normal . The known mildly displaced rib fracture is not appreciated .
    OUTPUT:
    
Bibasilar atelectasis . Known mildly displaced rib fracture is not appreciated .