Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates a normal cardiomediastinal silhouette and pulmonary vasculature . There are mild bibasilar opacities likely atelectasis . No definite pneumothorax or pleural effusion is identified .
    OUTPUT:
    
No definitive pneumothorax . Bibasilar atelectasis .