Objective To analyze the MRI features of rare intracranial germ cell tumors of the pineal region compared with pathologic findings.Methods The MRI and pathologic data of 32 patients with rare intracranial germ cell tumors of the pineal region were reviewed retrospectively.All cases were proved by surgery and pathological examinations.Results Fourteen teratomas with malignant transformations were cyst-solidary which were mixed signals on plain MRI and the solid components showed obvious enhancement.The adiposity signals could be seen in teratomas.The level of serum or CSF AFP was high.Microscopically,many tissue components could be seen.The signal of 6 yolk sac tumors were homogeneous,and they had great enhancement after enhanced scanning.Increasing of preoperative serum AFP level could be seen in all patients.The 5 embryonal carcinomas were well-defined margin masses and heterogeneous with cystoid variation and necrosis and moderate to severe edema.The solid components showed obvious enhance.The signals of 7 mixed germ cell tumors were atypical,which depended on the components of germ cell tumors.Conclusion The MRI findings of the rare intracranial germ cell tumors of the pineal region(teratomas with malignant transformations,yolk sac tumors endodermal sinus tumor,embryonal carcinomas and mixed germ cell tumors)show some feature which are correlated with pathology.Suggestive diagnosis could be made combined with clinical data and MRI features.

Objective To explore the MRI features of germ cell tumors in sellar regions for better developing clinical treatment plans.Methods The imaging and pathologic findings of 44 sellar germ cell tumors were retrospectively analyzed.Results There were 1 9 germinoma,most of which had clear boundaries,different extents of cystic necrosis and mild peritumoral edema.Lesions were significantly enhanced in contrast-enhanced MRI (CE-MRI).There were 8 cases with mature teratoma,most showed cystic-solid changes,presenting mixed-intensities on T1-weighted images and T2-weighted images.There were 1 1 malignant teratoma(im-mature teratoma and teratoma malformation ),however,there were more parenchymatous tissue in malignant teratoma than mature teratoma.Two yolk sac tumors showed uniform signals on T1-weighted images and T2-weighted images,significant enhancement on CE-MRI,and visibly higher AFP in serum.Two embryonal carcinomas had clear boundary,inhomogeneous intensities,visibly cyst-ic necrosis,median to servere peritumoral edema,the parenchyma showed significant enhancement in CE-MRI.The signals of two mixed germ cell tumors were not typical,which depended on the components within tumors.Conclusion The MRI features of germ cell tumors in sellar region are characteristic.