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 are unremarkable aside from patchy calcification along the aortic arch . The lungs appear clear . There are no pleural effusions or pneumothorax . Mild degenerative changes involve the lower thoracic spine .
    OUTPUT:
    
No evidence of acute disease .