Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The right lung volume is stable . Development of an opacity in the superior segment of the left lower lobe . Interval improvement of left pleural effusion . The cardiomediastinal and hilar will order is are stable . The right pleural surfaces are normal . Median sternotomy wires are intact . No pneumothorax
    OUTPUT:
    
1 . Slight improvement of small left pleural effusion . No pneumothorax 2 . Development of left lower lobe opacity may represent pneumonia , less likely atelectasis , infarction secondary to pulmonary embolism or iatrogenic hemorrhage secondary to recent thoracentesis . Correlation with clinical findings is recommended .