成人颅内原始神经外胚层肿瘤的MRI表现和病理对照

目的 探讨成人颅内原始神经外胚层肿瘤(primitive neuroectoderrnal tumors，PNET)的MRI特征，以期提高对该病的认识。方法回顾性分析了7例经手术和病理证实的成人颅内PNET的MRI表现，并与手术、病理相对照。结果 肿瘤多位于大脑半球和小脑蚓部，浸润性生长，瘤组织由低分化的小细胞构成，形态上可向多种细胞过渡。(2)MRI上肿瘤较大，4例呈浅分叶状，边界较清楚，瘤周水肿轻微；平扫呈不均匀较低T1、等或高T2信号，内部常伴有囊变和坏死区、可有出血和钙化；增强扫描6例肿瘤有明显的不均一强化；2例发生颅内转移，1例术后发生腰椎转移。结论 成人颅内PNET的MRI表现有一定特点；MRI有助于该病的诊断和指导治疗。

MRI features of intracranial primitive neuroectodermal tumors in adults:comparison with histopathological findings

Objective To evaluate the MRI features of intracranial primitive neuroectodermal tumors (PNET) in adults.Methods The MRI appearances were analyzed retrospectively in seven adult patients with pathologically proven intracranial PNET.The relationships between MRI features and findings in pathology and surgery were evaluated.Results (1) The tumor masses were most commonly found in the cerebral hemisphere or in the cerebellar vermis.They consisted of crowded undifferentiated small round cells and spread invasively.(2) The tumors were large and 4 were lobulated in shape.MR images showed the tumors to be middle or obviously hypointense on T_1 weighted images and hyperintense on T_2 weighted images.Most masses had heterogeneous appearances with some cystic and necrotic areas.Intratumoral haemorrhage and focal calcification were occasionally seen.All of them had well-defined margins.Mostly,there was no or only mild surrounding edema.Marked inhomogeneous contrast enhancement on MRI was seen in 6 cases except one.2 patients with multiple intracranial metastases were revealed on MR images.In this series,there was good correlation between MRI features and findings in pathology and surgery. Conclusion Certain MRI features may suggest the diagnosis of intracranial PNET in adults.MRI is an effective technique in detecting this tumor and is helpful to treatment planning and follow-up.