原始神经外胚叶肿瘤的影像诊断

目的分析原始神经外胚叶肿瘤(PNET)的CT、MRI表现,以提高对该病的认识。方法回顾分析29例经病理证实的PNET的临床表现和CT、MRI征象。结果原发于上肢PNET 3例,上颌窦1例,肺1例,纵隔2例,腹膜后2例,颈部1例,下肢2例,额叶6例,颞叶3例,脑室内3例,CPA区1例,椎管内2例,盆腔内2例。病灶体积较大,呈浸润生长,推压邻近结构,并可凸入椎管。肿瘤密度/信号不均,CT为软组织密度,轻至中度强化;MR T1WI肿块与肌肉等信号,T2WI呈不均匀高信号,增强扫描呈花环状或蜂窝状强化。3例有钙化,2例邻近骨质破坏,呈溶骨性破坏伴骨膜反应。肿瘤DWI上呈高信号,ADC值低于其他颅内原发性肿瘤。结论 PNET的常规MRI表现和DWI特点有助于其术前定性诊断和鉴别诊断。

The imaging diagnose of primitive neuroectodermal tumors

Objective To describe the conventional MR findings and the diagnostic value of MRI and CT in primitive neuroectodermal tumors so as to improve the diagnosis of this entity. Methods The conventional MRI and CT features were retrospectively analyzed in cases of primitive neuroectodermal tumors proved by operation and pathology, and diffu- sion weighted imaging feature of cases were retrospectively studied. Results Primary sites were upper limbs （n = 3）, maxillary sinus （n= 1）, lung（n=l）, mediastinum （n= 2）, retroperitoneum （n= 2）, neck（n= 1）, legs（n= 2）, fron- tal lobe（n= 6）, temporal lobe（n= 3）, intraventricular（n= 3）, CPA district（n= 1）, spinal canal（n=2）, and pevic cavi- ty（n= 2）. The tumors usually had big size with aggressive behavior, tended to displace adjacent soft tissue structures. Some case had calcification in tumor. Local or bony invasion in bone marrow involvement with periosteal new bone forma- tion were seen in a few patients. The tumors were tended to be round in shape with clear margin. The tumors were ap- peared slight hypointensity or isointensity on T1 weighted images and slight hyperintensity or isointensity on T2 weighted images, and surrounded by slight edema with enhanced markedly. Cyst, hemorrhage and necrosis could be observed in mi- nority tumors. The metastatic lesions through cerebrospinal fluid and distant metastasis lesions could be detected in a few cases. The tumors were appeared hyperintensity on diffusion weighted images and hypointensity on ADC map. Conclusion Combining the conventional MRI appearance with CT features can be helpful to diagnose primitive neuroectodermal tumors before operation and differentiate the tumors from other tumors. Radiologic appearance is not specific, but MRI and CT are useful in predicting prognosis and resectable, in detecting distant metastases, and in the evaluation of response to treatment.