Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle lower lobe opacities are seen which may be due to atelectasis , aspiration , or infection . No pleural effusion or pneumothorax is seen . The cardiac silhouette is top - normal . Mediastinal contours are unremarkable .
    OUTPUT:
    
Subtle lower lobe opacities may be due to atelectasis , aspiration , subtle infection not excluded .