Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are normally expanded . No focal airspace opacity is detected . There is perhaps minimal atelectasis at the left base , similar to the prior study . The heart is not enlarged . The mediastinal and hilar contours are normal . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
No evidence of acute cardiopulmonary abnormality .