Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low . The heart is normal in size . The mediastinal and hilar contours appear within normal limits . There is a patchy opacity obscuring the right heart border , probably reflecting slight opacification in the right middle lobe . The lungs appear otherwise clear . Bony structures are unremarkable .
    OUTPUT:
    
Right middle lobe opacity , probably due to minor atelectasis or scarring , although an infectious process can not be excluded in the appropriate setting . If available , comparison to prior radiographs might be helpful to determine chronicity if needed clinically .