Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The aortic arch is densely calcified . Otherwise , the cardiac , mediastinal and hilar contours are unremarkable . There is moderate relative elevation of the left hemidiaphragm compared to the right with patchy opacities in the left lower lung most suggestive of atelectasis . Chronicity of diaphragmatic elevation can not be assessed .
    OUTPUT:
    
Elevation of the left hemidiaphragm . It is difficult to exclude a retrocardiac opacity which may reflect atelectasis or pneumonia associated with this appearance , but possibly elevation is chronic with minor atelectasis or scarring .