Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size , mediastinal and hilar contours are normal . Lungs are clear except for a new linear atelectasis at the left lung base . There are no pleural effusions or pneumothoraces . Healed lower right rib fractures are again demonstrated .
    OUTPUT:
    
Linear left lobe atelectasis . No evidence of pneumonia .