Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Allowing for differences in modality , a moderate - sized left pleural effusion is improved since prior CT examination . Platelike atelectasis is noted at the left upper lobe . Known left perihilar mass and associated atelectasis is better assessed on prior CT examination . Note is also made of retrocardiac atelectasis . The right lung is clear . There is no pneumothorax .
    OUTPUT:
    
1 . Improved moderate left - sided pleural effusion . No pneumothorax . 2 . Known left perihilar mass and associated atelectasis is better assessed on prior CT examination .