Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since yesterday retrocardiac opacity and small opacity in the right infrahilar and right lower medial lung is much better , likely atelectasis or aspiration . Both upper lungs are clear . There is no pleural abnormality .
    OUTPUT:
    
Study yesterday , retrocardiac opacity and small opacity in right lower medial and infrahilar region has improved suggesting it was atelectasis or aspiration . There is no pleural abnormality .