Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild left base atelectasis / scarring , similar to prior . Prominence of the superior mediastinum remains , but is less evident as compared to the prior study . Cardiac silhouette is similar to prior . There is a retrocardiac opacity in the frontal view , which may be due to prominent mediastinal fat and hiatal hernia seen on CT from ___ . This retrocardiac opacity was seen dating back to at least ___ .
    OUTPUT:
    
Minimal left base atelectasis / scarring . Otherwise , no acute cardiopulmonary process .