目的 研究MRI成像对毛细胞型星 形细胞瘤的诊断价值。方法 回顾性分析 11例术前MRI检查术后病理证实为毛细胞 型星形细胞瘤的MRI资料，总结MRI信号特 征。结果 肿瘤发生在小脑的有7例，大脑 的有4例。11例病例中，完全囊性有2例， 囊实性的有6例，完全实性的有3例。出现 壁结节的有4例，有6例出现第四脑室受压 和幕上脑室积水。肿瘤的实性部分一般 T1WI呈低信号或等低信号，T2WI呈高信号 或等高信号，而DWI图像上实性部分表现 为低信号。增强后肿瘤实性部分明显强 化，囊性部分不强化。结论 毛细胞型星 形细胞瘤的MRI表现具有一定的特征性,磁 共振检查可作为首选术前诊断方法。

Objective To investigate the value of magnetic resonance imaging (MRI) for pilocytic astrocytoma (PA). Methods 11 patients with PA proven by pathology were selected in study, and their pre-operation MRI findings were analyzed and summarized retrospectively. Results Tumor located at cerebellum (7 cases) and cerebral hemisphere (4 cases) among all the 11 cases and could be classified as cyst (2 cases), cyst with nodule (6 cases) and mass (3 cases). Mural nodule appeared in 4 cases. Furthermore, displacement of the fourth ventricle and dropsy of supratentorial ventricle appeared in 6 cases. The solid component of tumor appeared as hypointense or isointense on T1WI, hyperintense or isointense on T2WI and hypointense on DWI. After administration of Gd-DTPA intravenously, the solid part showed obvious enhancement while the cystic part appeared little. Conclusion There is characteristic appearance of PA in MRI that could be a used as preferential method for pre-operation diagnosis.