脑毛细胞型星形细胞瘤的MRI诊断特点(附32例报告)

MRI characteristics of intracranial pilocytic astrocytoma

目的探讨脑毛细胞型星形细胞瘤的MRI表现,以提高诊断正确率。方法回顾性分析32例经手术病理证实的毛细胞型星形细胞瘤的临床及MRI特点。结果32例中,71.9%发生于20岁以下青少年人,其中小脑蚓部10例(31.3%),小脑半球9例(28.1%),鞍区7例(21.9%),基底节区和脑干各2例(6.3%),第三脑室内1例(3.1%),右侧颞叶1例(3.1%)。MRI上分四型:单囊型14例(43.8%)、多囊型12例(37.5%);实性型5例(15.6%);完全囊变型1例(3.1%)。肿瘤实性部分平扫T1WI为等或稍低信号,T2WI为等或稍高信号;囊性部分T2WI信号多比脑脊液信号高。增强扫描实性部分明显强化,呈蜂窝状。灶周无水肿28例(87.5%);4例灶周轻微水肿。结论毛细胞型星形细胞瘤的MRI表现有一定的特征性,结合患者的年龄及临床表现可以提高术前诊断率。

Objective To study the MR findings of intracranial pilocytic astrocytoma, as to improve the accuracy of diagnosis. Methods The clinical data and MR images of 32 cases with intracranial pilocytic astrocytoma proved by surgery and pathology were analyzed retrospectively. Results Pilocytic astrocytoma usually occurred in adolescent under 20 years old （ 71.9% ）. Ten of them located in the vemis of cerebellum （ 31.3 % ）, nine in the cerebellar hemisphere （28.1%） ,seven in the supreasellar region（21.9% ）, two in the basalganglia and in brain stem respectively（6. 3% ） ,one in the third ventricle and in the right temporal lobe respectively. The tumors could be divided into 4 types in MRI images： Single cyst with mural nodule （43.8%）, multiple cysts with mural nodule （37. 5% ）, predominantly solid mass （ 15.6% ） and cystic mass（3.1% ）. The solid components were isointensity or slightly hypointensity on T1 WI, and heterogeneous hyperintensity on T2WI. The cystic components of the tumors were hyperintensity compared to CSF. The solid components were obviously enhanced in honeycomb-shaped, which was of some characteristic. Twenty-eight lesions showed no obvious peritumoral edema（87. 5% ） ,four masses showed slightly mild peritumoral edema. Conclusions The MRI images of pilocytic astrocytoma had some typical features. Combination of the age and clinical data could improved the accuracy of diagnosis.