双能量CT对非小细胞肺癌淋巴结转移的诊断价值

Diagnostic value of dual energy CT for lymph node metastasis in patients with non-small cell lung cancer

目的:探讨双能量CT能谱曲线对非小细胞肺癌(NSCLC)患者淋巴结转移的诊断价值。方法:对40例NSCLC患者(鳞癌15例,腺癌25例)行双能量增强CT扫描,测量肺癌原发灶、肺门及纵隔内短径5 mm以上的淋巴结(共85枚,包括转移淋巴结53枚,非转移淋巴结32枚)在不同能量水平下(40~190 keV,间隔10 keV)的CT值,得到肺癌原发灶与胸腔淋巴结的CT能谱曲线,比较两者的CT能谱曲线斜率,判断淋巴结是否转移。采用受试者工作特征(ROC)曲线确定诊断淋巴结转移的CT能谱曲线斜率比值的最佳分界值,并对CT能谱曲线诊断NSCLC淋巴结转移的价值进行评估。结果:肺癌原发灶、转移淋巴结和非转移淋巴结的能谱曲线斜率分别为1.10±0.11、1.08±0.07和1.54±0.17,其中转移淋巴结与肺癌原发灶的曲线斜率差异无统计学意义(t=-1.32,P>0.05),非转移淋巴结与肺癌原发灶曲线斜率差异有统计学意义(t=-2.58,P<0.05)。转移淋巴结和非转移淋巴结与肺癌原发灶的能谱曲线斜率比值分别为0.98±0.05和1.40±0.12,两者差异有统计学意义(t=-2.86,P<0.05)。以能谱曲线斜率比值等于1.15作为淋巴结转移的分界值,CT能谱曲线诊断肺癌患者胸腔淋巴结转移的敏感度、特异度、阳性预测值、阴性预测值和准确率分别为81.1%、87.5%、91.5%、73.7%和83.5%。结论:双能量CT检查有助于提高NSCLC治疗前淋巴结分期的准确性。

Objective: To assess the diagnostic value of dual energy CT for lymph node metastasis in patients with non-small cell lung cancer(NSCLC). Methods: Forty NSCLC patients, including 15 cases of squamous cell carcinoma and 25 cases of adenocarcinoma, underwent dual energy CT examination in pre-contrast and venous phase contrast scans, then the CT attenuation value of the lung cancer lesions and 85 mediastinal enlarged lymph nodes(the short diameter ≥ 5 mm, 53 metastatic and 32 non-metastatic) were measured at different energy levels(40-190 keV, spacing10 keV) in venous phase contrast. CT spectral curves of the lung cancer lesions,hilus pulmonis and mediastinal enlarged lymph nodes were produced automatically, through comparing their CT spectral curves slope to judge whether or not the lymph nodes were metastatic. Receiver operating characteristic(ROC) curve was used to evaluate the efficiency of CT spectral curve in diagnosis of lymph node metastasis. Results: The CT spectral curves slopes of the lung cancer, metastatic lymph nodes and non-metastatic lymph nodes were 1. 10 ± 0. 11, 1.08 ± 0. 07 and 1.54 ± 0. 17,respectively. There was no significant difference in curve slope between metastatic lymph nodes and lung cancer(t=-1. 32, P > 0. 05); while there was significant difference between nonmetastatic lymph nodes and lung cancer(t =-2.58, P < 0.05). The CT spectral curve slope ratios of metastatic and non-metastatic lymph nodes to lung cancer were0.98±0. 05 and 1.40 ±0. 12,respectively(t=-2.86, P< 0.05). ROC curve showed that taking CT spectral curve slope ratio of 1. 15 as cut-off value for the diagnosis of metastatic lymph nodes, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 81. 1%, 87.5%, 91.5%, 73.7%and 83. 5%, respectively. Conclusion: Dual energy CT is of value in improving the diagnostic accuracy of lymph node metastasis in NSCLC patients before treatment.