Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette size is normal . The aorta is tortuous . The hilar contours are unremarkable . There is no pulmonary edema . Streaky opacities in the lung bases likely reflect atelectasis . No pleural effusion or pneumothorax is identified . There are multilevel degenerative changes in the thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .