Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Large left pleural effusion is minimally smaller since the next most recent study . There is persistent rightward shift of midline structures . The left upper lung and right lung appear clear . The heart is obscured . There is no large pneumothorax .
    OUTPUT:
    
Large left pleural effusion is minimally smaller without evidence of pneumothorax .