Fig. 3

How to define whether a tumor is ahead or on the side of the brainstem? a The maximum level axis tumor enhancement MRI is divided into two equal parts by the median sagittal line, and the pressed brainstem with a lateral displacement is across the median sagittal plane to the contralateral; tumor is believed to be ahead of the brainstem, expressed in the red “+.” b The maximum level axis tumor enhancement MRI is divided into two equal parts by the median sagittal line, and the pressed brainstem with a lateral displacement is not across the median sagittal plane to the contralateral; the tumor is believed to be the side of the brainstem. In the local amplification of b, the tumor is believed to be the side of the brainstem, expressed in the blue “−.” d–f The film in a–c and the yellow part is the brainstem