Characteristics Of Low-does Thin-section Computed Tomography With Three-dimensional Reconstruction In Micro Ground-glass Opacity And Selections Of Mediastinal Lymph Node Dissection Modes

Background:Ground-glass opacity(GGO)is generally considered as the precursors of lung cancer on imaging.With people's health consciousness and the accuracy of inspection,the detection rate of ground-glass opacity is higher than ever.Many studies have attempted to identify the characteristic imaging findings of GGO for the qualitative diagnosis;however,the endeavor is often hampered by the diverse radiological manifestations.Because the rate of lymphatic metastases in small GGO is not high,academia fails to reach agreement on the mode for mediastinal lymph node dissection.This study was performed to identify imaging features of GGO and select a better mode of mediastinal lymph node dissection.Methods:We retrospectively evaluated 90 patients with isolated small pulmonary ground-glass opacities and the resected lymph nodes(with the exclusion of benign lesions),pathologically examined after surgical resection.Nine imaging characteristics were assessed:size,shape,location,a solid component,air cavity density,vascular convergence sign,lobulation,spiculation and pleural tag.Differences of these characteristics between malignant and benign nodules were analyzed using t test,chi-square test and binary logistic regression.The lymph nodes was classified according to latest version 8 TNM stage.Results:Of the 90 GGOs,there were 65 malignant nodules and 25 benign nodules.Irregular shape,vascular convergence sign,and spiculation were risk factors for malignancy,with sensitivity,specificity and accuracy of 89.2%,76.0%and 85.6%respectively.Meanwhile,air cavity densities,lobulation and pleural tags were helpful to diagnosis solitary GGOs,with positive predictive values of 93.5%,83.3%and 85.1%respectively.Of 65 groups of lymph nodes,mediastinal lymph node metastasis were observed in 6 patients,4 patients with N1 type and 2 patients with N2 type.The rate of lymph node metastasis was 9.2%.Conclusion:Irregular shape,vascular convergence sign,and spiculation are important indicators of malignancy.Solitary GGOs with air cavity densities,lobulation and pleural tags should also be suggestive of malignancy.In addition,systematic mediastinal lymph node dissection are unnecessary and pulmonary lobe specific lymph node dissection(PLSLND)should be recommended.Moreover,we highly recommend low-does thin-section computed tomography with three-dimensional reconstruction to obtain a comprehensive and accurate analysis of the nodules.