Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is at the upper limits of normal size . The mediastinal and hilar contours appear within normal limits . Patchy right infrahilar opacity has remained the same and so is probably due to minor atelectasis or scarring . Otherwise , the lungs appear clear . There are no pleural effusions or pneumothorax . Slight degenerative changes are similar along the thoracic spine .
    OUTPUT:
    
No evidence of acute disease .