Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . There is no pleural effusion or pneumothorax . The lungs appear clear . Hardware associated with fixation of the sternum appears unchanged . The sternum and anterior ribs are difficult to assess with radiography , but there is no convincing radiographic evidence for bone destruction .
    OUTPUT:
    
No evidence of acute abnormality .