Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size appears mildly enlarged but unchanged . The aortic knob is calcified . Mediastinal and hilar contours are similar . Marked emphysematous changes are again demonstrated . Mild bibasilar atelectasis is noted . No focal consolidation , large pleural effusion or pneumothorax is present . Compression deformities involving vertebral bodies within the mid and lower thoracic spine appear unchanged .
    OUTPUT:
    
Severe emphysema . Mild bibasilar atelectasis .