Objective: To evaluate the value of minimum ADC(ADC(min))and mean ADC(ADC(mean)), lesion to spinal cord signal intensity ratio (LSR) in diagnosis of metastatic hilar and mediastinal lymph nodes in patients with lung cancer. Methods: A total of 34 patients (89 lymph nodes) pathologically diagnosed as lung cancer were enrolled into this study who were examined in the Second Affiliated Hospital of Nantong University from January 2016 to June 2017. All patients underwent MRI scan 1 week before surgery or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). The short-axis diameter, ADC(mean) and ADC(min) of lymph nodes were measured and recorded respectively by two radiologists.The signal intensity of lymph nodes and spinal cord was also measured on DWI images (b=800 s/mm(2)). According to pathological findings, all lymph nodes were divided into metastasis group (58 lymph nodes) and non-metastasis group(31 lymph nodes). An independent sample t-test was used to compare the differences between the two groups of short-axis diameter, LSR, ADC(mean) and ADC(min) between two groups.The diagnostic performance of short-axis diameter, LSR, ADC(mean) and ADC(min) was analyzed by ROC curves. Results: There were significant differences in short-axis diameter, ADC(mean), ADC(min) and LSR values between two groups (all P<0.01). The short-axis diameter and LSR of the metastatic group were higher than that in non-metastasis group, while ADC(mean) and ADC(min) in metastatic group were lower than that in non-metastasis group.The ROC curve analysis showed that ADC(mean), ADC(min) and LSR achieved excellent but comparable diagnostic performance with an AUC of 0.977, 0.972 and 0.941, respectively (P<0.05). While the short-axis diameter of lymph nodes demonstrated poor diagnosis performance with an AUC of 0.798 (P<0.05). The thresholds of short-axis diameter, ADC(mean), ADC(min) and LSR were 9.86 mm, 1.88×10(-3) mm(2)/s, 1.57×10(-3) mm(2)/s and 0.80, respectively.Sensitivity, specificity, positive predictive value, negative predictive value and accuracy for ADC(mean) were 96.6%, 90.3%, 94.9%, 93.3% and 94.4%, respectively, and those for ADC(min) were 98.3%, 90.3%, 95.0%, 96.6% and 94.4%, respectively, those for LSR were 91.4%, 90.3%, 94.6%, 84.8% and 89.9%, respectively, while those for short-axis diameter were 79.3%, 71.0%, 83.6%, 64.7% and 76.4%, respectively.There were significant differences in the area under the ROC curve between short-axis diameter and LSR, short-axis diameter and ADC(mean), short-axis diameter and ADC(min) (P<0.05). But there was no significant difference in the area under ROC curve between LSR and ADC(mean), LSR and ADC(min), ADC(mean) and ADC(min) (P>0.05). Conclusion: LSR, ADC(min) and ADC(mean) are the reliable parameters for the differentiation of metastatic and non-metastatic lymph nodes in lung cancer patients, and have good performance.
目的： 评估表观扩散系数最小值(ADC(min))、表观扩散系数平均值(ADC(mean))、病灶脊髓信号强度比(LSR)诊断肺癌肺门纵隔淋巴结转移的价值。 方法： 回顾性分析2016年1月至2017年6月在南通大学第二附属医院就诊的肺癌患者34例(89枚淋巴结)。所有患者均经手术或超声内镜引导下经支气管针吸活检术(EBUS-TBNA)取得病理，并于术前行MRI＋DWI检查。测量并记录淋巴结最大短径(T(2)WI图像)、ADC(mean)、ADC(min)及高b值时淋巴结和胸髓的信号强度。以病理结果为金标准，分为转移组(58枚)和非转移组(31枚)。采用独立样本t检验及受试者工作特征曲线(ROC)分析两组淋巴结上述四种指标差异并评估其诊断效能。 结果： 两组淋巴结的短径、ADC(mean)、ADC(min)及LSR差异均有统计学意义(均P<0.01)，转移组短径、LSR高于非转移组，ADC(min)及ADC(mean)低于非转移组。上述指标ROC曲线下面积(AUC)分别为0.798、0.977、0.972和0.941。ADC(mean)取阈值1.88×10(－3) mm(2)/s、ADC(min)取1.57×10(－3) mm(2)/s、LSR取0.80时均有较好的诊断敏感度、特异度、阳性预测值(PPV)、阴性预测值(NPV)及准确性(ADC(mean)分别为96.6%、90.3%、94.9%、93.3%、94.4%；ADC(min)分别为98.3%、90.3%、95.0%、96.6%、94.4%；LSR分别为91.4%、90.3%、94.6%、84.8%、89.9%)。短径阈值为9.86 mm，但诊断效能欠佳(敏感度为79.3%、特异度为71.0%%、PPV为83.6%、NPV为64.7%、准确性为76.4%)。短径分别与LSR、ADC(mean)及ADC(min)的AUC比较差异均有统计学意义(均P<0.05)，LSR与ADC(mean)、LSR与ADC(min)及ADC(mean)与ADC(min)比较AUC差异均无统计学意义(均P>0.05)。 结论： LSR、ADC(min)、ADC(mean)对肺癌肺门纵隔淋巴结转移均显示了较高的诊断价值，有一定的临床应用价值。.
Keywords: Diffusion magnetic resonance imaging; Lesion to spinal cord signal intensity ratio; Lung neoplasms; Lymph nodes.