CT和MRI对颅内表皮样囊肿诊断价值的评价

目的：评估CT和MRI对颅内表皮样囊肿的诊断价值，分析误诊原因，提高诊断水平。方法：44例经手术和病理证实的颅内表皮样囊肿，术前全部行常规MRI检查，其中19例行Gd-DTPA增强MRI检查；17例作CT平扫，其中12例作静脉注射增强CT检查。结果：颅内表皮样囊肿多位于桥小脑角池，本组病例中占34．9％(15／4例)；肿瘤多呈不规则形态，占70．45％(31／44例)；CT平扫多呈均匀低密度，占70．59％(12/17例)，造影后多无强化，占91．71％(11／12例)；MRT1加权像上多呈均匀低信号，但略高于脑脊液，T2加权像上多呈均匀高信号，占61．36％(27／44例)，Gd-DTPA增强后多无强化，占84．21％(16／19例)。肿瘤周围的脑组织均无水肿，占100％，肿瘤较大时可以挤压、推移周围脑组织或脑室结构，引起比较明显的占位效应，占70．45％(31／44例)；肿瘤较大时，很少引起阻塞性脑积水。结论：颅内表皮样囊肿在CT和MRI像上有特征性表现，MRI无论在定位和定性诊断上优于CT，Gd-DTPA的应用有助于颅内囊性占位的诊断与鉴别诊断。

Evaluation of CT and MR imaging in diagnosis of intracranial epidermoid cyst

Objective:To evaluate the diagnosis value of CT and MRI of intracranial epidermoid cyst.Methods:44 patients with intracranial epidermoid cyst,proven by surgery and pathology,were examined with routine MR imaging and 19 cases with MR imaging after injection of Gd DTPA; 17 cases were examined with plain CT scan and 12 cases with post contrast CT scan.Results:34.09% (15/44) of tumors were located in CPA. 70.45% (31/44) of tumors were irregular shaped.70.59% (13/17) of tumors were homogeneous low density on plain CT Scan and 91.67% (11/12) of tumors showed no enhancement.61.36% (27/44) of tumors showed homogeneous hypointense signal on T 1WI and hyperintense signal on T 2WI; 84.21% (16/19) of tumors showed no enhancement after Gd DTPA. There was no edema around tumor in all cases. Mass effect could be seen in 31 cases and hydrocephalus was seldom seen in this study.Conclusion:The CT and MRI manifestation of intracranial epidermoid cyst is characteristic.Compared with CT,MR imaging is superior in locating and quality of the lesion, Gd DTPA is helpful in differentiating epidermoid cyst from other cystic lesions.