Abstract: Objective Dual-source CT(DSCT)energy imaging was used to analyze the difference of energy spectrum parameters and energy spectrum curves between mediastinal metastatic lymph nodes and non-metastatic lymph nodes in non-small cell lung cancer(NSCLC).The relationship between DSCT standardized iodine concentration and energy spectrum curve with mediastinal lymph node metastasis was discussed.Methods A total of 113 patients with NSCLC underwent DSCT energy imaging scans.Iodine images were obtained at the processing workstation.The normalized iodine concentrations of all mediastinal lymph nodes and energy spectrum curves at different energy levels were measured.According to the pathological results,the patients were divided into lymph node metastasis group and non-lymph node metastasis group.The normalized iodine concentration and energy spectrum curve slope of the two groups were analyzed by t-test.The best threshold of standardized working iodine concentration was calculated by receiver operating characteristic curve(ROC)to diagnose the mediastinal lymph node metastasis of NSCLC.Results There was a significant difference in the normalized iodine concentration between the two groups of mediastinal lymph nodes in NSCLC(P＜0.05);The ROC curve was used to calculate the standardized iodine concentration for the diagnosis of NSCLC.The optimal threshold for lymph node metastasis was 52.45%;The energy spectrum curve of mediastinal lymph nodes in NSCLC was gradually decreasing.There was a significant difference between the two groups in the range of 40~110 keV interval(P＜0.05).Conclusion The quantitative analysis of DSCT energy imaging parameters is of great significance in the diagnosis of mediastinal lymph node metastasis in NSCLC.It can be used as an important index for preoperative judgment of lymph node metastasis in NSCLC.

Key words: Dual-source CT, Non-small cell lung cancer, Lymph nodes, Standardized iodine content