Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . The lung volumes are low with mild elevation of the right hemidiaphragm . Patchy opacities at the lung bases are probably compatible with atelectasis , and not out of proportion to reduced lung volumes , but potential are infectious .
    OUTPUT:
    
Mild retrocardiac opacification , atelectasis versus pneumonia .