Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Again , subtle streaky left base retrocardiac opacity could be due to atelectasis / scarring or pneumonia or aspiration . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Subtle streaky left base retrocardiac opacity could be due to atelectasis / scarring or pneumonia or aspiration .