Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette size is mildly enlarged . The aorta is tortuous and diffusely calcified . The mediastinal and hilar contours are otherwise unremarkable . The pulmonary vasculature is not engorged . Patchy opacities within the lung bases likely reflect areas of atelectasis without focal consolidation . No large pleural effusion or pneumothorax is identified . There are mild to moderate degenerative changes noted in the lower thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .