Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs remain clear , without new focal opacity to suggest pneumonia . Scarring is again noted at the left lung base . There is no pleural effusion or pneumothorax . Intact median sternotomy wires and mediastinal surgical clips are again noted . Hilar and cardiomediastinal contours are unchanged . There is calcification and tortuosity of the descending aorta . There is no free air identified under the hemidiaphragms .
    OUTPUT:
    
Persistent left basilar scarring . No acute cardiopulmonary process .