Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The aortic arch is enlarged and oval in shape which may represent an aneurysm . There is no pleural effusion or pneumothorax . The lungs appear clear . Slight degenerative changes are noted along the thoracic spine .
    OUTPUT:
    
Possible aortic aneurysm . No definite evidence of acute disease .