Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are slightly low with vascular crowding . There is no evidence of pneumonia . There is mild atelectasis at the lung bases , left greater than right . Heart size is normal . The mediastinal and hilar contours are normal . There is no large pleural effusion or pneumothorax .
    OUTPUT:
    
No acute cardiopulmonary abnormality . Mild bibasilar atelectasis .