Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal . The aorta is tortuous but unchanged . Mediastinal and hilar contours are stable . The pulmonary vascularity is not engorged . Minimal atelectasis is noted in both lung bases . There is no focal consolidation , pleural effusion or pneumothorax . No acute osseous abnormality is identified . Mild degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .