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目的探讨3.0T高分辨扩散加权成像(DWI)在颅内表皮样囊肿诊断中的价值。方法回顾性分析18例表皮样囊肿的临床资料和影像学表现。所有病例均行3.0T MRI扫描,包括平扫、增强及DWI检查。通过测量表皮样囊肿、脑脊液及正常脑白质在不同序列上的信号强度,分别计算肿瘤-脑脊液、肿瘤-脑白质的信号强度比值及对比度。另外分别测量病灶、脑脊液及正常脑白质的表观扩散系数(ADC)值。结果病灶位于桥小脑角区7例,四脑室2例,桥前池1例,小脑蚓部1例,颞部4例,鞍区1例,脑干腹侧1例,海绵窦区1例。表皮样囊肿ADC值(0.95±0.16)×10-3 mm2/s,低于脑脊液,高于脑白质(P<0.01)。肿瘤-脑白质比值最高的是T2WI,为4.12±0.89,其次是DWI,为2.39±0.36;肿瘤-脑脊液比值最高的是液体衰减反转恢复序列,为12.04±0.79,其次是DWI,为8.35±0.85。结论表皮样囊肿多位于脑外,需同时显示其与脑脊液和正常脑白质的对比,3.0T高分辨DWI提供了良好的表皮样囊肿与正常脑白质及脑脊液对比,具有较强特征性,是颅内表皮样囊肿最有价值的MRI检查方法。
Objective To investigate the value of 3.0T high resolution diffusion weighted imaging (DWI) in the diagnosis of intracranial epidermoid cyst. Methods Retrospective analysis of 18 cases of epidermoid cyst clinical data and imaging findings. All cases underwent 3.0T MRI scan, including plain scan, enhanced and DWI examination. By measuring the signal intensity of epidermoid cysts, cerebrospinal fluid and normal white matter in different sequences, the signal intensity ratio and contrast of tumor-cerebrospinal fluid and tumor-brain white matter were respectively calculated. In addition, the apparent diffusion coefficient (ADC) values of lesions, cerebrospinal fluid and normal white matter were measured respectively. Results The lesions were located in 7 cases of cerebellopontine angle, 2 cases of 4-compartment, 1 case of bridge anterior, 1 case of cerebellar vermis, 4 cases of temporal lobe, 1 case of saddle, 1 case of ventral brainstem and 1 case of cavernous sinus. Epidermoid cyst ADC value (0.95 ± 0.16) × 10-3 mm2 / s, lower than cerebrospinal fluid, higher than white matter (P <0.01). The highest ratio of tumor-to-brain white matter was T2WI, which was 4.12 ± 0.89, followed by DWI, which was 2.39 ± 0.36. The highest tumor-CSF ratio was 12.04 ± 0.79, followed by DWI, 8.35 ± 0.85. Conclusions Epidermoid cysts are mostly located outside the brain and need to be compared with cerebrospinal fluid and normal white matter. The 3.0T high resolution DWI provides good contrast between epidermoid cysts and normal white matter and cerebrospinal fluid. Endothelial dermoid cyst is the most valuable MRI examination.