Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal . Mediastinal silhouette and hilar contours are stable . A subtle retrocardiac density is noted , new from ___ . There is no pleural effusion or pneumothorax . Extensive fixation hardware is visualized in the thoracic spine .
    OUTPUT:
    
New retrocardiac density which is likely atelectasis given patient 's clinical improvement without therapy as discussed with Dr . ___ ___ by ___ over the telephone on ___ at 11 : 15 a .m . .