Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . There is similar streaky retrocardiac opacity that can probably be attributed to atelectasis . Elsewhere , the lungs appear clear . There is no definite pleural effusion . No pneumothorax is seen .
    OUTPUT:
    
Left basilar opacity , not significantly changed , which suggests atelectasis . No definite evidence of acute disease .