Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are very low which causes crowding of bronchovascular structures . Within this limitation there is relatively no change compared to the prior chest radiograph . No focal opacity , pleural effusion or pneumothorax is identified . The cardiac and mediastinal contours are stable .
    OUTPUT:
    
Very low lung volumes . Within this limitation there is no focal opacity concerning for pneumonia .