Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle right middle lobe opacity which may be due to atelectasis although an early infectious process is not excluded in the appropriate clinical setting . The left lung is clear . The hilar contours are stable . The cardiac silhouette is not enlarged . The aorta is slightly tortuous .
    OUTPUT:
    
Subtle right middle lobe opacity most likely represents atelectasis although an early infectious process is not excluded in the appropriate clinical setting .