原发性颅内毛细胞星形细胞瘤的MRI与扩散特征分析

Diffusion-weighted MRI Features of Primary Pilocytic Astrocytoma in Intracalvarium

目的:探讨原发性颅内毛细胞星形细胞瘤的常规MRI与扩散特征。方法:回顾性分析17例经手术、病理证实的原发性颅内毛细胞星形细胞瘤的常规MRI、MR扩散加权成像(DWI)特征,定量测定肿瘤实质和对侧正常脑白质区表观扩散系数(ADC)的值,比较两者平均ADC值的差异。结果:17例毛细胞星形细胞瘤MRI表现为囊性部分呈长T1长T2信号,实性部分呈等、稍长T1等、稍长T2信号。增强扫描可以分为不强化的囊壁及显著强化的壁结节、环形强化的囊壁及显著强化的壁结节、单纯环形强化的囊壁、实性肿瘤的均匀强化、肿瘤大部分为实性成分的不均匀强化等几种。肿瘤DWI低信号15例,等低混杂样信号2例,SWI可见低信号2例,信号低于对侧正常脑实质,ADC值升高。瘤体ADC值为(1.46～1.93)×10-3mm2/s,高于肿瘤对侧正常脑实质区的ADC值(0.86～1.26)×10-3mm2/s,差异有统计学意义(t=7.139,P<0.01)。结论:在传统的MRI序列基础上,应用DWI成像技术对于毛细胞星形细胞瘤的诊断及鉴别诊断具有重要作用。

Objective To study the conventional MRI, diffusion-weishted imaging （DWI） characteristics of primary pilocytic astrocytoma in intracalvarium. Methods Seventeen patients with pilocytic astrocytoma in intracalvarium were confirmed pathologically, and the conventional MRI and DWI features of the pilocytic astrocytoma were observed. The apparent diffusion eodecient （ADC） values from the solid portion of tumor and the normal contralateral white matter were measured quantitatively, Results MRI characteristics of the 17 patients were as follows. The cystic part was hypo-intensity and parenchymal part was iso-intensity or hypointesity on T^-weighted image, and the cystic part was hyper-intensity and parenchymal part was iso-intensity or hyper-intensity on T2-weighted one. After contrast injection, the lesions were usually enhanced as follows： cystic tumor with a nonenhancing cyst wall （only the mural nodule was enhanced）; cystic tumor with an enhanced cyst wall （the mural nodule and the cyst wall were enhanced）; cystic tumor with an enhanced cyst wall（only the cyst wall was enhanced）; solid tumor（regular contrast enhancement）; mainly solid tumor（most with irregular contrast enhancement）. On DWI, the solid portion of tumors showed hypointensity in 15 patients, isointensity or hypointesity in 2 patients, and 2 patients had hypointesity on SWI. On ADC map, the solid portion of tumors showed hyperintense. The ADC value of the solid portion of tumors was （1.46-1.93）×10-3 mm2/s. The ADC value of the normal contralateral white matter was （0.86-1.26）×10-3 mm2/s. There was statistically significant difference in mean ADC value between the solid portion of tumors and normal contralateral white matter （t=7.139, P〈0.01）. C.,oncluaion The conventional MRI combined with DWI is of great importance for the diagnosis and differential diagnosis of piloeylic astrocytoma. [Chinese Medical Equipment Journal, 2012,33 （9） ： 61-63,76]