Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear unchanged . There is no pleural effusion or pneumothorax . Slight subpleural thickening at each lung apex is probably unchanged . Otherwise , the lungs appear clear . Minimal degenerative changes are similar along the mid thoracic spine .
    OUTPUT:
    
No evidence of acute disease .