Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild atelectasis at the left base . The remainder of the lungs are clear without focal opacities to suggest pneumonia . The cardiomediastinal silhouette , hilar contours , and pleural surfaces are normal . There is no large pleural effusion or pneumothorax .
    OUTPUT:
    
Mild atelectasis at the left base without evidence of pneumonia .