Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . Vague supradiaphragmatic opacities in both lower lobes compatible with atelectasis . No focal opacity concerning for pneumonia . There is no pleural effusion or pneumothorax . Multiple healed right posterior rib fractures are reidentified .
    OUTPUT:
    
Bibasilar atelectasis but no focal opacity concerning for pneumonia .