Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Midline tracheostomy tube is seen . There are relatively low lung volumes and persistent mild elevation of the right hemidiaphragm . Left base retrocardiac opacity is seen which could be due to atelectasis however , underlying consolidation due to infection or aspiration may be present . No large pleural effusion is seen although trace pleural effusions would be difficult to exclude . There is no evidence of pneumothorax . The cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Left base retrocardiac opacity atelectasis versus consolidation which could be due to infection or aspiration .