颅内生殖细胞瘤的影像学诊断

Imagingdiagnosis of intracranial germinoma

目的探寻颅内生殖细胞瘤的CT和MRI特点。方法回顾性分析18例经病理或放疗证实的颅内生殖细胞瘤患者的CT和MRI表现。结果18例颅内生殖细胞瘤患者中，9例位于松果体区，3例位于基底节区及丘脑，6例位于鞍区。松果体区肿瘤MRI呈长T1、等或长T2信号，边缘光滑，出血少见，CT呈均匀等密度或稍高密度，松果体钙化常被肿瘤包埋，增强呈均匀显著强化。鞍区肿瘤垂体柄增粗，垂体后叶正常短T1信号消失，肿瘤T1WI呈等信号，T2WI上信号可以表现为等或高信号，CT上肿瘤实体部分呈高密度，增强扫描有明显强化。基底节及丘脑肿瘤，瘤体较大，信号及密度不均匀，边缘欠清晰，出血多见，增强呈不均匀强化。结论颅内生殖细胞瘤影像学表现具有一定的特征性，结合临床表现可进一步提高诊断正确率。

Objective To explore CT and MRI appearances of intracranial germinoma. Methods Eighteen patients with intracranial germinoma confirmed histologically and radiotherapy were selected as the object of this study. CT and MR findings of germinoma were analysed retrospec- tively. Results In 18 cases, the tumors were located at pineal region in 9 cases, the basal ganglia and thalamus in 3 cases and the sellar region in 6 cases. Germinoma of pineal region showed low signal intensity on T1WI, iso or hyperintense on T2WI, isodense or slightly hyperdense on CT with definite margin, the pineal calculus were embedded frequently by tumors. After administration of contrast material, the tumors showed marked and uniformity enhancement. Thickness of pituitary stalk and absence of the hyperintensity of the posterior pituitary on T1WI were found in sellar germinoma. Tumors showed isointensity on T1WI, but variable signal intensity was exhibited on T2WI. Calcification was absent in all cases, but the solid components of tumors were hyperdense on plain CT, and they were obvious enhancement on contrast -enhanced images. Germinoma located at basal ganglia and thalamus showed larger volume of tumors, inhomogeneous signal intensity and density with indefinite margin, hemorrhage seen in most of case. After administration of contrast material, the tumors showed patch or chaplet - like enhancement. Conclusions It is possible to make the preoperative diagnosis for intracranial germinoma according to sex, age and CT,MR imaging characteristics.