Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patchy opacity is noted in the left lung base , which may reflect either early developing pneumonia or aspiration . Mild bibasilar atelectasis is noted . The heart size is normal . Mild blunting of the left costophrenic angle may reflect a small pleural effusion or mild pleural thickening . A midline tracheostomy is noted . Median sternotomy wires are intact and aligned . No pulmonary edema or pneumothorax .
    OUTPUT:
    
Persistent left basilar opacity may reflect either pneumonia or aspiration .