Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate multiple sternotomy wires . Again seen is a widened mediastinum , which is improved compared to prior radiograph , presumably secondary to slowly resolving hematoma . A small left pleural effusion is also improved . Cardiomegaly is unchanged . The lung fields appear clear . No pneumothorax or bony abnormality is seen .
    OUTPUT:
    
1 . A widened , postoperative mediastinum is improving over the past week , presumably secondary to slowly resolving hematoma . 2 . Small left pleural effusion , decreased over the past week .