Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear unchanged . There are streaky opacities at the left lung base but decreased compared to the prior study , most suggestive of improving atelectasis . There is no pleural effusion or pneumothorax . Internal - external biliary drains have been revised in two internal drains .
    OUTPUT:
    
Improvement in opacification at the left lung base . Interval exchange of internal - external for internal biliary drains .