Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart is normal size and mediastinal silhouette is stable . Calcifications are again noted in the aortic arch . Diffuse lucencies in the mid to upper lungs bilaterally , correspond to severe centrilobular emphysema . There is no focal consolidation , pleural effusion , or pneumothorax . Bones and the upper abdomen are grossly unremarkable .
    OUTPUT:
    
No acute intrathoracic abnormality . Severe upper lobe predominant emphysema .