Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: An endotracheal tube is present 4 .4 cm from the carina . The lung volumes are low . Opacities in the right medial base and retrocardiac region are present . There is no pulmonary edema , pleural effusion , or pneumothorax . The mediastinal contours are slightly widened , likely exacerbated by low lung volumes . The cardiac size is unremarkable .
    OUTPUT:
    
1 . Appropriate positioning of the endotracheal tube . 2 . Bibasilar opacities could be due to atelectasis ; alternatively , in the proper clinical setting , could be due to aspiration .