| Objective:Explore the clinical application value of spectral CT of multi-parameter gemstone imaging(GSI)in the assessment of regional lymph node metastasis in non-small cell lung cancer prospectively.Methods:prospectively,36 cases were collected pathologically confirmed non-small cell lung cancer with mediastinal lymphadenopathy in the first consultation at The First Affiliated Hospital of Nanchang University from March 2019 to September 2019.All patients underwent surgical lymph node dissection and/or endobronchial ultrasound guided tranbronchial needle aspiration.Two chest CT diagnosticians with more than 10 years of working experience,together with surgical related doctors,matched the positions of lymph nodes clearly diagnosed qualitatively by pathology or cytology with the positions in the energy spectrum CT image.According to the pathological results of lymph nodes,two groups were divided into metastatic lymph node group and non-metastatic lymph node.Imaging physicians use energy spectrum CT post-processing software to perform energy spectrum analysis on scanned CT images without knowing the pathological results.Measure and calculate the arterial and venous phases of40-100 keV spectrum curve(HU Curve Slope,?HU),40-100 keV spectrum curve slope(?HU ratio),normalized iodine concentration(NIC)of all lymph nodes And Arterial Enhancement Fraction(AEF).The independent sample t test was used to compare the differences between the parameters of the metastatic lymph node group and the non-metastatic lymph node group.p <0.05 indicated that the difference was statistically significant.Analysis of receiver operating characteristic curve was performed on the statistically different energy spectrum parameters between the metastatic and non-metastatic lymph nodes,and the area under the curve was calculated to evaluate differential diagnosis efficiency of each parameters.Then,the best critical value of each parameter weredetermined according to the Youden index.Results:1.A total of 36 cases were enrolled.6 females and 30 males,aged 26 to 75 years,with an average of 55.34 ± 10.75 years.24 cases of adenocarcinoma,10 cases of squamous cell carcinoma,and 2 cases of large cell carcinoma.There were 136 lymphadenopathy and 95 lymph nodes that met the conditions of the study,including31 metastatic lymph nodes and 64 non-metastatic lymph nodes.2.The scan image results were based on the maximum short diameter of the lymph nodes greater than 10 mm as the diagnostic criteria for lymph node metastasis.The diagnosis of 27 metastatic lymph nodes and 36 non-metastatic lymph nodes was correct.4 lymph nodes were missed.28 lymph nodes were misdiagnosed.The diagnostic sensitivity was 87.1%,the specificity was 56.3%,the accuracy was 66.3%,the positive predictive value was 49.1%,and the negative predictive value was 90%.3.The mean of lymph nodes in metastatic and non-metastatic groups of arterial phase?HU,arterial phase?HU ratio and AEF were(1.630 ± 0.730)vs(1.844 ±0.841),(1.293 ± 0.919)vs(1.469 ± 0.976)and(0.718 ± 0.284)Vs(0.707 ±0.282).There was no significant difference between the three groups respectively(p =0.230,p = 0.404 and p = 0.856).The mean values of venous ?HU,venous ?HU,arterial and venous NICs were(2.211 ± 0.567)vs(2.705 ± 0.720),(1.113 ±0.303)vs(1.523 ± 0.415),(0.150 ± 0.094)vs.(0.195 ± 0.092)and(0.427 ±0.116)vs(0.561 ± 0.171).The difference was statistically significant respectively(p = 0.001,p <0.001,p = 0.030,and p <0.001).4.ROC curve analysis were performed on the above-mentioned statistically different indicators.The energy spectrum curve ratio in venous phase has the highest diagnostic efficiency with AUC 0.803.The optimal critical value is calculated based on the Youden index.When the curve ratio was equal to 1.465,the sensitivity was93.5% and the specificity was 60.9%;the second was the parameter of normalized iodine concentration in venous phase with AUC 0.755;when the normalized iodine concentration in venous phase is equal to 0.482,the sensitivity was 83.9% and the specificity was 67.2%.Conclusion:Gemstone spectral CT of multi-parameter spectroscopic imaging has certain clinical diagnostic value in evaluating the status of mediastinal lymph node metastasis in non-small cell lung cancer.1.The difference between venous ?HU,venous ?HU ratio,and arterial and venous NIC between metastatic lymph node group and non-metastatic lymph node group werestatistically significant.The average diameter in metastatic lymph node group was lower than the non-metastatic lymph node group.2.There was no statistically significant difference of ?HU in arterial phase,? HU ratio in arterial phase and AEF between metastatic lymph node group and non-metastatic lymph node group.3.According to the analysis of ROC curve,the ratio of ?HU in venous phase,NIC in venous phase and ?HU in venous phase have moderate diagnostic power;NIC in arterial phase has low diagnostic power.The diagnostic efficiency of the venous phase energy spectrum curve ratio was the highest.When the venous phase energy spectrum curve ratio of 1.460 or the venous phase normalized iodine value of0.482 was the diagnostic threshold,the diagnostic efficiency is better than that of the largest short diameter of the lymph nodes greater than 10 mm. |
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