The Study Of Gemstone Spectral Imaging In The Diagnosis Of Lymph Node Metastasis Of Non-small Cell Lung Cancer

Part I The application of gemstone spectral CT in improving the diagnostic accuracy of preoperative status of lymph nodes in non-small cell lung cancer[Objective] To prospectively evaluate the diagnostic accuracy of gemstone spectral CT in improving the diagnostic accuracy of preoperative status of lymph nodes in non-small cell lung cancer (NSCLC).[Method] Fifty-nine consecutive patients proven NSCLC pathologically who underwent spectral CT scan were enrolled. One hundred and one sets of monochromatic images were generated ranging from 40 keV to 140 keV. All 59 cases in this group received surgical treatment, and were compared with pathological results. Draw receiver operator characteristic (ROC) curve to determine the optimal cut-off point of ratio of λHu and ratio of normalized iodine concentration (NIC) to improve the diagnostic value of metastatic lymph nodes.[Result] There was no significant difference between λHu value of metastatic lymph nodes (n=31) and the correlative primary tumors (n=17) [(1.86±0.85) vs. (1.76±0.67), p =0.627]. Statistical difference of λHu value was shown between non-metastatic lymph nodes (n=65) and the correlative primary tumors (n=42) [(2.09±0.77) vs. (1.49±0.65),p =0.000]. Significant difference of ratio of λHu was shown between metastatic and non-metastatic lymph nodes [(1.05±0.26) vs. (1.54±0.59),p=0.000]. The cut-off point of ratio of λHu in assessment of metastatic lymph nodes was 1.31 determined by ROC curve method. Thus, the sensitivity, specificity, AUC value were 64.6%,90.3%,0.789, respectively. There was no significant difference between NIC value of metastatic lymph nodes (n=31) and the correlative primary tumors (n=17) [(0.20±0.09) vs. (0.20±0.07), p=0.696]. Statistical difference of NIC value was shown between non-metastatic lymph nodes (n=65) and the correlative primary tumors (n=42) [(0.76+0.07) vs. (0.17+0.08), p=0.000]. Significant difference of ratio of NIC was shown between metastatic and non-metastatic lymph nodes [(1.05±0.28) vs. (1.48±0.66), p=0.001]. The cut-off point of ratio of NIC in assessment of metastatic lymph nodes was 1.23 determined by ROC curve method. Thus, the sensitivity, specificity, AUC value were 64.6%、80.6%、0.740, respectively.[Conclusion] Spectral Hu curve and material differentiation analysis on gemstone spectral CT is proved to be helpful in improving the diagnostic accuracy of preoperative status of lvmph nodes in NSCLC.Part II Study on related factors to regional lymph node metastasis before surgery of patients with non-small cell lung cancer[Objective] To analyse the possible related factors to the diagnosis of regional lymph node metastasis and determine whether the spectral parameters can be the efficient factors in diagnosis.[Materials and Methods] Fifty-nine NSCLC patients underwent curative surgical resection after performing enhanced gemstone spectral CT scan were enrolled, with full and accurate clinical, pathological, and imaging materials. The possible risk factors of lymph node metastasis were analysed. Two classification variables were analysed by Pearson χ2 test, and rank variables were analysed by Linear-by-Linear Association χ2 test. Variables which with statistic differences were analysed by multivariate logistic regression model.[Results] In the study of the risk factors which may affecting the node metastasis, age, location of lesion, size of lesion, size of lymph node, ratio of λHu, ratio of NIC were elected into the logistic regression model stepwise backward. Logistic multivariate analysis showed that age, size of lymph node, ratio of λHu were significant diagnostic factors for lymph nodal metastasis in NSCLC patients. Lymph nodes which were larger than 10mm were diagnosed as metastasis 12 times than smaller ones (95%CI=2.816～50.273). Lymph nodes whose ratio of λHu between 0.7 and 1.3 were diagnosed as metastasis 14 times than others (95%CI=1.137-172.891).[Conclusion] Ratio of λHu, ratio of NIC, size of lymph node, size of lesion, location of lesion, age are factors significantly associated with lymph node metastasis. Larger lymph nodes(≥10mm) and ratio of λHu (0.7～1.3) are factors which are more valuable than others.