Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The contour of the mediastinum suggests a tortuosity or mild dilatation of the ascending thoracic AA or . In all other respects the cardiomediastinal silhouette and pulmonary vasculature are normal . The lungs are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
No acute intrathoracic abnormality .