Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: No pneumothorax status post thoracentesis . Substantial improvement in the left pleural effusion . Left lower lung atelectasis persists . The right lung is essentially clear . Heart size is normal . The mediastinum is not widened . The hila are within normal limits .
    OUTPUT:
    
Substantial decrease in left pleural effusion and no pneumothorax after left thoracentesis .