Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette size is normal . Aortic knob is calcified . Mediastinal and hilar contours are unchanged , and there is no pulmonary vascular congestion . Severe emphysematous changes are most pronounced at the lung apices . Increased interstitial markings at the lung bases may reflect atelectasis and / or scarring . There is evidence of hyperinflation . No pleural effusion or pneumothorax is seen . Several clips are noted within the mediastinum . There are no acute osseous abnormalities , though the bones are diffusely demineralized .
    OUTPUT:
    
Severe emphysema . Mild bibasilar atelectasis and / or scarring .