Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is top normal . The mediastinal and hilar contours are unchanged , with calcification of the aortic knob redemonstrated . The pulmonary vascularity is normal . Linear opacities in both lung bases are compatible with subsegmental atelectasis . No focal consolidation , pleural effusion , or pneumothorax is present . No acute osseous abnormality is seen .
    OUTPUT:
    
Mild bibasilar subsegmental atelectasis .