Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette size is normal . There is mild calcification of the aortic knob . The mediastinal and hilar contours are within normal limits . The pulmonary vascularity is normal . Lungs are clear . No pleural effusion , focal consolidation or pneumothorax is present . There are multilevel degenerative changes in the thoracic spine .
    OUTPUT:
    
No acute cardiopulmonary abnormality .