Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval improved aeration at the left lung base . No focal consolidation , pneumothorax , or pulmonary edema is seen . Mild blunting of the right costophrenic angle may be secondary to small effusion or scarring . Lung volumes are slightly low , which may exaggerate heart size ; heart and mediastinal contours appear stable with mild cardiomegaly . Median sternotomy wires are again noted .
    OUTPUT:
    
Improved aeration at the left lung base without evidence for acute cardiopulmonary process .