Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is mildly enlarged . Moderate unfolding is noted along the thoracic aorta , as before . The cardiac , mediastinal and hilar contours appear unchanged . Similar to the prior examination , there are patchy opacities in each lower lung , more extensive on the right than left , probably due to patchy atelectasis or scarring . Aeration is somewhat improved on each side . Subpleural scarring is unchanged at each lung apex . A Bochdalek hernia on the left is unchanged in contour . Mild degenerative changes are similar along the thoracic spine .
    OUTPUT:
    
Improved aeration at the lung bases , but with persistent patchy opacification , particularly at the right lung base .