Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The lung volumes are low . The mediastinal and hilar contours are unremarkable . There is no pleural effusion or pneumothorax . The lungs are clear . Posterolateral fractures involving the left fourth , fifth , and sixth ribs appear old and healed .
    OUTPUT:
    
No evidence of acute disease .