Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . A linear left upper lobe opacity suggests minor atelectasis or scarring , but otherwise the lungs appear clear . There is no pleural effusion or pneumothorax . Bony structures are unremarkable . There is mild rightward convex curvature centered along the lower thoracic spine .
    OUTPUT:
    
No evidence of acute disease .