Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP and lateral radiographs of the chest demonstrate clear lungs with mild bibasilar atelectasis . The cardiac , mediastinal , and hilar contours are stable since the prior study . Mitral valve replacement is noted in the lateral view and intact median sternotomy wires are seen . No pneumothorax or pleural effusion . Ossification of the anterior longitudinal ligament indicative of DISH .
    OUTPUT:
    
Stable mediastinal contour with mild bibasilar atelectasis .