Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Decreased density within the bilateral upper lobes is compatible with the patient 's known centrilobular emphysema . A subtle right lower lobe opacity is essentially unchanged from ___ . There are no new airspace opacities are identified , and there is no pleural effusion or pneumothorax . The patient is status post median sternotomy , and the cardiomediastinal silhouette is stable .
    OUTPUT:
    
No evidence of acute cardiopulmonary process .