Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a small to moderate left pleural effusion , unchanged . Left retrocardiac opacification is likely due to atelectasis given the findings on the recent CT from ___ . There is mild bandlike right lower lung atelectasis , new compared to the prior study . The heart size is normal . There is no pneumothorax .
    OUTPUT:
    
1 . Unchanged small to moderate left pleural effusion . 2 . Left retrocardiac opacification , most likely atelectasis .