Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Relatively linear opacity at the left lung base is felt to more likely represent atelectasis rather than pneumonia . The right lung is clear . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are unremarkable .
    OUTPUT:
    
Subtle linear in configuration left base opacities felt to more likely represent atelectasis rather than pneumonia . No pneumothorax seen .