Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The aortic knob is calcified . Mediastinal and hilar contours are otherwise unremarkable . There is no pulmonary vascular congestion . No focal consolidation , pleural effusion or pneumothorax is seen . Minimal patchy opacities in the lung bases likely reflect atelectasis . There are mild degenerative changes within the thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .