Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette size is top normal . The mediastinal and hilar contours are unremarkable . There is minimal atelectasis at the lung bases . No pleural effusion or pneumothorax is identified . No acute osseous abnormality is noted , but an old left mid clavicular fracture is seen .
    OUTPUT:
    
Mild bibasilar atelectasis .