MRI弥散加权成像对鼻咽癌T分期的应用研究

目的研究MRI弥散加权成像对鼻咽癌(NPC)T分期的应用价值。方法选取2015年4月至2017年2月我院对鼻咽部病变行常规MRI及DWI检查的患者50例为研究对象,其中病理证实为鼻咽癌30例,良性病变20例,另以同期入院体检的健康志愿者20例为对照组,分析鼻咽部良恶性病变影像特点,比较鼻咽癌患者原发灶、受累肌肉、受累斜坡的表观扩散系数值(ADC)与对照组差异,应用ROC曲线分析各ADC诊断阈值诊断鼻咽癌的敏感性、特异性,同时分析MRI及DWI诊断鼻咽癌T分期的准确率。结果 NPC原发灶及受累肌肉内瘤灶在T1WI序列呈等低信号,T2WI轴位显示两侧鼻咽部软组织对称性增厚,边界清,呈稍高信号,DWI则见鼻咽部软组织呈稍高信号,ADC图呈低信号,与鼻咽良性病灶相比在信号特征、增强方式、生长方式、累及范围方面有不同特征;NPC原发灶、受累肌肉、受累斜坡ADC值(0.746±0.085)×10~(-3)mm~2/s、(0.765±0.091)×10~(-3)mm~2/s、(0.762±0.089)×10~(-3)mm~2/s]明显低于对照组(P0.05);NPC原发灶、受累肌肉、受累斜坡的ADC诊断阈值分别为0.832×10~(-3)mm~2/s、0.860×10~(-3)mm~2/s、0.557×10~(-3)mm~2/s,其诊断灵敏度依次为93.2%、86.1%、98.6%,特异度依次为85.9%、66.9%、65.4%;MRI及DWI联合诊断鼻咽癌T分期的准确率90.00%高于单独MRI 56.67%或DWI 66.67%(P0.05)。结论MRI及弥散加权成像结合有助于对鼻咽癌良恶性病变进行鉴别,可较好显示鼻咽癌原发瘤与其邻近受累结构,对鼻咽癌T分期评估具有较高应用价值。

Application Study of MRI Combined with Diffusion Weighted Imaging in T Staging of Nasopharyngeal Carcinoma

Objective To study the application values of MRI combined with diffusion weighted imaging in T staging of nasopharyngeal carcinoma.Methods 50 cases of patients with nasopharyngeal lesions treated with conventional MRI and DWI examination in our hospital from April 2015 to February 2017 were selected for the research. 30 cases of nasopharyngeal carcinoma and 20 cases of benign lesions were confirmed by pathology and the other 20 healthy volunteers hospitalized in the same time period were selected as the control group. The imaging features of benign and malignant nasopharyngeal lesions were analyzed. The differences of the apparent diffusion coefficient (ADC) between the primary lesion, the affected muscles and the affected slopes in nasopharyngeal carcinoma patients were compared with those in the control group. The sensitivity and specificity of each ADC diagnostic threshold in diagnosis of nasopharyngeal carcinoma were analyzed by ROC curve, and the accuracy rates of MRI and DWI in diagnosis of T staging in nasopharyngeal carcinoma were analyzed.Results Low signals were shown in NPC primary lesion and affected muscle intestine lesion in the T1WI sequence, and symmetrical thickening of both sides of the nasopharyngeal soft tissue with clear boundaries and slightly higher signal were displayed in the T2WI axial position. What's more, slightly high signal was showed in nasopharyngeal soft tissue in DWI while low signal in ADC. Compared with nasopharyngeal benign lesions there were different characteristics in the aspects of signal characteristics, enhancement patterns, growth patterns and involved scope. The ADC values of NPC primary lesion,the affected muscle and the affected slope(0.746±0.085)×10-3mm2/s, (0.765±0.091)×10-3mm2/s, (0.762±0.089)×10-3mm2/s] were significantly lower than those in the control group (P<0.05). The ADC diagnostic thresholds of NPC primary lesion, the affected muscle and the affected slope were 0.832×10-3mm2/s, 0.860×10-3mm2/s, 0.557×10-3mm2/s, the diagnostic sensitivity was 93.2%, 86.1%, 98.6%, the specificity was 85.9%, 66.9% and 65.4% respectively. The accuracy rate of MRI and DWI with 90% in the diagnosis of T staging in nasopharyngeal carcinoma was higher than that of MRI with 56.67% or DWI with 66.67% (P<0.05). Conclusion MRI combined with diffusion weighted imaging can help the differential diagnosis of benign and malignant nasopharyngeal carcinoma, and can better show primary tumor and its adjacent affected structure in the nasopharyngeal carcinoma. Therefore it has high application value for T staging assessment nasopharyngeal carcinoma.