Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours are within normal limits . There is minimal atherosclerotic calcification of the aortic arch . The pulmonary vasculature is normal . Minimal streaky opacity within the left lung base may reflect an area of atelectasis but infection can not be excluded . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities .
    OUTPUT:
    
Minimal patchy opacity in the left lung base . This could reflect an area of atelectasis but infection can not be excluded in the correct clinical setting .