Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded . Minimal opacification of the left base most likely reflects atelectasis . The cardiomediastinal silhouette is normal . The thoracic aorta is calcified and unfolded as before . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
No definite evidence of pneumonia . Minimal opacification of the left base likely reflects atelectasis .