目的分析颅内毛细胞星形细胞瘤MRI表现及特点。方法 回顾性分析经手术、病理证实的17例毛细胞星形细胞瘤MRI表现。17例中，小儿11例，成人结果6例。其中幕下11例（64.7%）。肿瘤12例为囊实性，4例为囊性，1例为实性。肿瘤边缘光整，伴有轻度水肿者6例，梗阻性脑积水12例，瘤内出血3例。肿瘤囊性成分T1WI呈低信号，T2WI呈高信号；肿瘤实性部分、囊壁T1WI呈等、稍低信号，T2WI呈等、稍高信号。增强后，实性部分明显强化，囊壁不强化或轻度强化，囊性部分不强化。结论  毛细胞星形细胞瘤好发于小儿，成人患者发病相对较少，肿瘤多为囊实性，MRI表现有一定的特征性，可提高其术前诊断准确性。

Objective To evaluate the MRI imaging features of intracranial pilocytic astrocytoma. Methods A retrospective analysis was made to the MRI manifestations of pilocytic astrocytoma in 17 cases confirmed by operation and pathologic study. Results Of all the 17 patients,11 cases were children,6 cases were adults,11 cases were in infratentorial region(64.7%).12 cases were cystic-solid, 4 cases were completely cystic degeneration,1 case was solid. The tumors had clear edges, 6 cases had peritumoral edema and 12 cases had obstructive hydrocephalus,3 cases presented with hemorrhage. The cystic part appeared as hypointensity on T1WI and hyperintensity on T2WI. The solid part of the tumors, the cystic wall manifested iso-hypointensity on T1WI, and iso-hyperintensity on T2WI. After the injection of contrast media, the solid part showed significant enhancement while the cystic wall showed no enhancement or slight enhancement, the cystic part showed no enhancement. Conclusion The pilocytic astrocytoma is usually seen in children and teenagers, adults are relatively less. Most of tumors are cystic-solid, MRI of pilocytic astrocytoma has characteristic imaging findings, which may improve the accurate diagnosis for preoperative clinic.