Comparison of the value of different measuring parameters in the diagnosis of mediastinal lymph node metastases in patients withlung adenocarcinoma on 18F-FDG PET/CT

Abstract Background 18F-FDG PET/CT has been used worldwide for the staging of lung cancer, but the criteria used for classifying mediastinal lymph nodes as malignant are underdispute. The aim of this study was to evaluate the diagnostic ability of using different standardized uptake value (SUV) parameters in the detection of mediastinal lymph node metastases of lung adenocarcinoma. Method A retrospective review of 61 patients with lung adenocarcinoma who underwent18F-FDG PET/CT from 2015 to 2018 in the nuclear medicine department of our hospital was performed. Patients with mediastinal lymph nodes shown on PET/CT and who underwent apathological examination were enrolled in our study. Different SUV parameters (e.g.,mediastinal lymph node SUVmax, node/liver SUVmax ratio, and node/mediastinum SUVmax ratio) were evaluated.Histology was used as the gold standard to evaluate the diagnosis of mediastinal lymph node metastasis. Receiver operating characteristic(ROC) curves were used to evaluate the accuracy of the three methods mentioned above. A Pvalue <0.05 was considered statistically significant. Results The pathological examination confirmed lymph node metastasis in 42 of 104 lymph node sections from 50 patients.The lymph node SUVmax, node/liver SUVmaxratio, and node/mediastinum SUVmax ratio of metastatic lymph nodes were higher than those of benign lymph nodes (P<0.05). The areas under the ROC curves of themediastinallymph node SUVmax, node/liver SUVmax ratio, and node/mediastinum SUVmax ratio were 0.81, 0.88, and 0.83, respectively, with cut-off values of 3.15,1.65, and 1.73, respectively. Conclusion The mediastinal lymph node SUVmax, node/liver SUVmax ratio, and node/mediastinum SUVmax ratio each have quite high accuracy in the detection of mediastinal lymph node metastases of lung adenocarcinoma, and a node/liver SUVmax ratio≥1.65 has higher accuracy than the other two parameters.