Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal . The aorta remains tortuous . Mediastinal and hilar contours are . Pulmonary vasculature is not engorged . Patchy opacities in the lung bases likely reflect atelectasis . No pleural effusion or pneumothorax is identified . There are multilevel degenerative changes noted in the thoracic spine .
    OUTPUT:
    
Mild atelectasis in the lung bases .