Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to the prior study , there is aeration of the left upper lobe , with persistent opacity in the left lower hemithorax , which likely represents a combination of atelectasis and residual pleural effusion . There is no pneumothorax . The right lung is well expanded and clear . Previously noted mild rightward shift of the mediastinum has improved .
    OUTPUT:
    
Interval improvement in the left lung aeration . Persistent left lower hemithorax opacity , likely represents residual atelectasis / pleural effusion .