Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The mediastinal and hilar contours are unchanged . The pulmonary vasculature is normal . Apart from mild atelectasis in the lung bases seen , the lungs are clear without focal consolidation . No pleural effusion or pneumothorax is present . Moderate degenerative changes are re - demonstrated in the thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .