Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The mediastinal and hilar contours are unchanged , with mild tortuosity of the thoracic aorta again noted . The pulmonary vasculature is normal . Minimal linear opacities in the lung bases likely reflect atelectasis . No focal consolidation , pleural effusion or pneumothorax is visualized . There are no acute osseous abnormalities .
    OUTPUT:
    
Mild bibasilar atelectasis . No radiographic evidence for pneumonia .