毛细胞星形细胞瘤的CT、MRI诊断分析

目的探讨毛细胞型星形细胞瘤的CT、MRI特征。方法回顾性分析8例经手术病理证实的毛细胞型星形细胞瘤的CT及MRI表现。结果（1）病变好发于小脑，8例毛细胞星形细胞瘤中，起源于幕下者5例。幕上者3例。（2）肿瘤呈类圆形，伴不同程度囊变，根据囊变程度可分为囊肿型、囊肿结节型和肿块型，以囊肿结节型最多见；（3）肿瘤囊性部分CT平扫呈低密度，MR平扫T1WI呈明显低信号，T2W1呈明显高信号；肿瘤实性部分、囊壁及壁结节CT呈等或稍低密度，MRT1W1呈等或稍低信号，T2WI呈稍高信号。增强后肿瘤囊壁不强化或轻度强化，壁结节及实性部分明显强化，囊性部分不强化；（4）肿瘤边界清楚，瘤周无水肿；（5）肿瘤出血与钙化少见。结论毛细胞型星形细胞瘤在CT、MRI表现具有一定特征性，可为临床术前提供信息。

Diagnosis of Pilocytic Astrocytoma by CT and MRI

Objective To discuss the CT and MRI imaging features of pilocytic astrocytoma. Methods A retrospective analysis was made to the CT and MRI manifestations of pilocytic astrocytoma in 8 cases confirmed by operation and pathologic study. Result The lesions usually located in cerebellum,out of the 8 cases,5 were supratentorial and 3 were subtentorial; the tumors were of round shape with cystic degeneration of different degrees, according to the cystic degeneration degrees ,the lesions could be divided into several types： cystic type, cysto - nodule type, which was most frequently found, and mass type; CT plain scanning revealed a hypodense of cystic part of the tumors while MRI plain scanning found an obvious low signal on T1WI and an obvious high signal on T2WI; the solid part of the tumors,the cystic wall and wall nodules manifested isodense or slight hypodense in CT images and obvious isointense or slight low signal on T1WI and slight high signal on T2WI in MRI images; after the injection of contrast media, the cystic wall of the tumors showed no enhancement or just slight enhancement, the wall -nodules and the solid part of the tumors showed obvious enhancement while the cystic part of the tumors showed no enhancement ; the tumors had clear edges, with no edema around; hemorrhage and calcification of the tumors were seldom found. Conclusions The CT and MRI manifestations of pilocytic astrocytoma are of characteristic features and provide imformation for clinic before operation.