Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are normally expanded . Faint opacity at the left base is not visualized on the lateral view . There is no pleural effusion or pneumothorax . The mediastinal and hilar contours are normal . The heart is not enlarged .
    OUTPUT:
    
No definite acute abnormality . Opacity at the left base likely reflects summation of normal structures .