Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are unchanged . The pulmonary vasculature is not engorged . Patchy opacities are seen within the lung bases . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities . Mild degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Bibasilar patchy opacities , likely atelectasis .