Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is top normal with mild tortuosity of the thoracic aortic arch . The mediastinal silhouette and hilar contours are otherwise unremarkable . Low lung volumes accentuate the cardiopulmonary vasculature . The lungs are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
No acute cardiopulmonary abnormality .