中文摘要：

目的：探讨1.5T 磁共振扩散加权成像（diffusion-weighted imaging,DWI）对鼻咽癌颈部小淋巴结转移瘤的诊断价值,寻求鼻咽癌小淋巴结转移瘤的表观弥散系数（apparent diffusion coefficient,ADC）诊断阈值。方法收集经病理证实的40例鼻咽癌患者的颈部淋巴结 MRI 常规平扫、增强扫描及 DWI 影像学资料,分别测量颈部转移性大淋巴结组、转移性小淋巴结组和良性淋巴结组的 ADC 值,运用 SPSS16.0统计学软件对各组 ADC 值进行差异性分析,采用受试者工作特征（receiver operating characteris-tic,ROC）曲线确定鼻咽癌颈部小淋巴结转移瘤的 ADC 诊断阈值并研究其诊断效能。结果颈部转移性大淋巴结组和小淋巴结组ADC 值分别为（0.74±0.11）×10-3 mm2/s 和（0.75±0.13）×10-3 mm2/s,二者间差异无统计学意义（P 〉0.05）；良性淋巴结组 ADC 值为（1.05±0.18）×10-3 mm2/s,与转移性小淋巴结组和转移性大淋巴结组 ADC 值差异均有统计学意义（P〈0.05）；以0.908×10-3 mm2/s作为鼻咽癌颈部小淋巴结转移瘤的 ADC 诊断阈值,其诊断特异性及敏感性分别为90.9%、83.2%,曲线下面积为0.92。结论MRI 扩散加权成像对鼻咽癌颈部小淋巴结转移瘤具有较高的诊断价值。

英文摘要：

Objective To study the diagnostic value of 1.5T diffusion-weighted magnetic resonance imaging for small metastatic cervical lymph nodes of nasopharyngeal carcinoma（NPC）,and to explore the optimal diagnostic threshold value of apparent diffusion coefficient（ADC）in small metastatic cervical lymph nodes of NPC.Methods 40 patients with histopathologically confirmed NPC were underwent conventional,enhanced and DWI MR.The mean ADC value of large metastatic cervical lymph nodes group,small metastatic cervical lymph nodes group and benign lymph nodes group were measured respectively.Statistical analysis was done by using the SPSS 1 6.0 program software.The receiver operating characteristic （ROC）curve was performed to obtain the ADC thresh-old value of small metastatic cervical lymph nodes and the diagnostic efficacy.Results The mean ADC value of large metastatic cer-vical lymph nodes group was （0.74±0.1 1）×10 -3 mm2/s,which was not significantly different from that in small metastatic cervical lymph nodes group（0.75±0.13）×10 -3 mm2/s,P 〉0.05.The mean ADC value in benign lymph nodes group was （1.05± 0.18）× 10 -3 mm2/s,which was significantly higher than that in large metastatic cervical lymph nodes group and small metastatic cervical lymph nodes group（P 〈0.05 ）.Using a threshold ADC value of 0.908 × 10 -3 mm2/s for differentiating small metastatic cervical lymph nodes from benign lymph nodes,a sensitivity of 83.2% and specificity of 90.9% were obtained,the area under the ROC curve was 0.92.Conclusion DWI is helpful in the diagnosis of small metastatic cervical lymph nodes of NPC.