弥散加权成像与MRI增强诊断表皮样囊肿的比较研究

Diagnosis of epidermoid cyst:comparison of the value of diffusion-weighted MRI and gadolinium-enhanced MRI

目的:比较弥散加权成像(DWI)与MRI增强(CE-MRI)对表皮样囊肿的检出敏感性,评价DWI的临床应用价值。方法:对59例初次检查及66例术后复查疑似表皮样囊肿的患者行回顾性研究,所有病例均行常规序列〔T1WI、T2WI、液体衰减反转恢复序列(FLAIR)〕、弥散加权成像(DWI)和钆对比剂增强扫描(CE-MRI)检查。将所有图像分为DWI结合常规序列(Ⅰ组)、CE-MRI结合常规序列(Ⅱ组)及DWI联合CE-MRI并结合常规序列(Ⅲ组)三组进行判断,诊断结果与手术病理进行比较,判定三组检查方法的敏感性,组间比较采用配对资料的χ2检验。另外选择32例经病理及随访观察证实的蛛网膜囊肿做对照,分析信号特征并测量ADC值,与表皮样囊肿ADC值的比较采用配对t检验。结果:Ⅰ组、Ⅱ组诊断表皮样囊肿的敏感性分别为90.5%、57.8%,二者具有明显统计学差异(χ2=25.714,P<0.01)。Ⅲ组诊断表皮样囊肿的敏感性为91.8%,与II组具有明显统计学差异(χ2=30.250,P<0.01),与I组没有统计学差异(χ2=0.250,P>0.05)。病理证实的88例表皮样囊肿DWI均呈明显高信号,32例蛛网膜囊肿DWI均呈明显低信号,表皮样囊肿的ADC值(1.06±0.21×10-3)mm2/s明显低于蛛网膜囊肿的的ADC值(3.24±0.39×10-3)mm2/s,两者比较差异有统计学意义(t=-3.647,P<0.01)。结论:DWI较MRI增强检查对表皮样囊肿具有较高的检出率,在与蛛网膜囊肿的鉴别及判断表皮样囊肿复发上能提供有价值的诊断信息。

Objective：To compare the sensitivity of diffusion weighted imaging （DWI） with contrast-enhanced magnetic resonance imaging （CE-MRI） in detecting epidermoid cyst and to evaluate the clinical value of DWI. Methods：The patients having an epidermoid cyst by clinically suspected were retrospectively stuied, including 59 cases of initial examination and 66 cases of after surgery. All patients underwent Conventional TIWI. T2WI, fluid attenuated inversion recovery （FLAIR）. diffusion weighted imaging （DWI） and gadolinium-enhanced MRI （CE -MRI）. All images were analyzed in three groups： DWI combined with conventional sequences （T1WI, F2 W1, FLAIR） （group I ）, CE-MR1 combined with conventional sequences （group II）, and DWI. CE-MRI and both combined with conventional sequences （group Ill）. Diag- nostic results were compared with surgical pathology results, which were regarded as the standard of reference. Sensitivi- ties were assessed and compared among the three methods using the X2 test for paired data. 32 cases of arachnoid cyst con- firmed by pathology and follow-up observation were selected as control. The signal characteristics were analyzed and the ADC values were measured meanwhile. The ADC values of arachnoid cyst and epidermoid cyst were compared with paired t test. Results：The diagnostic sensitivities of epidermoid cyst in group I and group Ⅱ were 90.5% and 57.8% respectively, and the difference was statistically significant （X2 ： 25. 714, P 〈0.01）. The diagnostic sensitivity of epidermoid cyst in group II1 was 91.8%. Group Ⅲ had significant statistical difference with group II （Xz =30. 250, P 〈0.01）, but not with group I （X2：0. 250, P 〉0.05）. DWI showed a significantly higher signal in 88 cases of epidermoid cyst confirmed by pa- thology, and a significantly lower signal in 32 cases of arachnoid cyst. The ADC values of epidermoid cyst （1.06±0.21×103）mm2/s were significantly lower than the ADC values of arachnoid cyst （3.24±0.39×10-3） mm2/s, so the difference was statistically significant （ t =- 3. 647, P 〈0.01）. Conclusion： DWI is more sensitive to detect epidermoid cyst than CE- MR1. It is useful to diagnose the recurrence of the disease, and can provide valuable differential diagnostic information a-bout epidermoid cyst and arachnoid cyst.