Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Tracheostomy tube projects over the midline of the upper thoracic trachea . Again seen is a moderate - sized left pleural effusion . Streaky left perihilar opacities while possibly representing atelectasis , could represent infection . Retrocardiac opacification likely represents left lower lobe collapse . The right lung is clear and slightly hyperinflated . Cardiomediastinal silhouette is normal .
    OUTPUT:
    
Persistent moderate left pleural effusion with left perihilar opacitites possibly representing atelectasis or infection .