Fig. 1

Computed tomography (CT) and magnetic resonance imaging (MRI) performed on admission. a Non-contrast CT, b T1-weighted imaging, c T2-weighted imaging, d T2* imaging, e gadolinium-enhanced T1 imaging (axial), and f sagittal reconstructed imaging. The tumor comprised a solid and a cystic component. The solid part was slightly calcified. The posterior wall of the cyst was adjacent to the floor of the fourth ventricle. g Gadolinium-enhanced T1-weighted imaging (Gd-T1WI) in the sagittal plane was performed on postoperative day 1, which showed the residual tumor (double arrows). h Gd-T1WI in the sagittal plane performed on postoperative day 43 showed marked enlargement of the gadolinium-enhanced solid component. i Gd-T1WI in the same slice as (g, h), which was obtained 4 years after tumor resection and irradiation. Slight shrinkage of the solid component was observed. The arrow indicates the tumor in (a–f), and the double arrows point to the postoperative residual tumor in (g–h)