Study On PET/CT Multi-parameter Diagnosis Of Benign And Malignant Mediastinal Lymph Nodes

Objective:To explore the value of ¹⁸F-FDG PET/CT multi-parameters in the diagnosis of benign and malignant mediastinal lymph nodes of non-small cell lung cancer?NSCLC?.Methods:The imaging and clinical data of patients who do PET/CT examination in the Department of Nuclear Medicine of Hebei General Hospital from July 2013 to December 2019 were analyzed retrospectively.According to the pathological or follow-up results of mediastinal lymph nodes,the patients were divided into two groups:malignant group?n=83?and benign group?n=91?.The malignant group included adenocarcinoma?n=58?,squamous cell carcinoma?n=17?,large cell carcinoma?n=1?and other types?n=7?.The benign group included sarcoidosis?n=2?,inflammatory pseudotumor?n=3?,necrotizing lymphadenitis?n=1?,granulomatous inflammation?n=1?,lymphadenitis?n=58?,lung cancer?n=21?and no examination,and 22 PET/CT and clinical parameters were obtained.There were 2 clinical parameters?age,sex?and 14 mediastinal lymph node parameters?SUVmax,SUVmean,MTV,TLG,lymph node SUVmax/mediastinal blood pool SUVmax,lymph node length diameter,short diameter,aspect ratio,necrosis,fat,calcification,symmetry,CT value,lymph node CT value/mediastinal blood pool CT value?.In addition,there were 6 parameters of primary lesion of lung cancer in the malignant group?length and diameter of primary focus,SUVmax,T stage,location,pathological type and whether the mediastinal lymph nodes were ipsilateral to the primary lesion?.Mann-Whitney U test was used to compare the parameters of 14 mediastinal lymph nodes in the benign and malignant group of mediastinal lymph nodes.The parameters with statistical difference were incorporated into the neural network multilayered perceptron?MLP??P<0.05?,to select the parameters with more than 50%importance of standardization to establish the model.Receiver operating characteristic curve?ROC?and the area under receiver operating curve?AUC?were used to evaluate the diagnostic efficacy of the model in differential diagnosis of benign and malignant mediastinal lymph nodes.In the malignant group of mediastinal lymph nodes,the parameters of mediastinal lymph nodes?SUVmax,MTV,TLG,ipsilateral and symmetrical with the primary lesion of NSCLC?were analyzed by Spearman rank correlation with the length and diameter of primary focus and SUVmax of primary lesion of lung cancer.In the mediastinal lymph node malignant group,the differences of SUVmax of primary lung cancer in different T stages and different primary sites were tested by Mann-Whitney U test,and the differences of SUVmax in different pathological types of lung cancer were compared by Kruskal-Wallis H test.Results:1.There were significant differences in 11 mediastinal lymph node parameters?SUVmax,SUVmean,MTV,TLG,lymph node SUVmax/mediastinal blood pool SUVmax,short diameter,aspect ratio,necrosis,fat,calcification,symmetry?between benign and malignant groups of mediastinal lymph nodes,?P<0.05?.There was no significant difference in lymph node length,CT value,lymph node CT value/mediastinal blood pool CT value,?P>0.05?.2.Four parameters of standardized importance>50%were selected from 11 parameters with statistical difference between benign and malignant groups of mediastinal lymph nodes by MLP,which were lymph node MTV,SUVmax,aspect ratio and short diameter of lymph nodes.ROC analysis showed that the best cut-off points of the above four parameters were1.219cm³,4.836,1.452,10.316mm and AUC were 0.772,0.776,0.657,0.731.The AUC of the combination of the four parameters was 0.831?P<0.05?.3.In the malignant group of mediastinal lymph nodes,the SUVmax and TLG of mediastinal lymph nodes were positively correlated with the SUVmax of primary lung cancer?r=0.318,0.151,P<0.05?.The distribution of mediastinal lymph nodes on the ipsilateral side was negatively correlated with the length and diameter of primary focus and SUVmax of lung cancer,?r=-0.139?-0.201,P<0.05?,while the symmetrical distribution of mediastinal lymph nodes was positively correlated with the length and diameter of primary focus and SUVmax of lung cancer?r=0.164,0.161,P<0.05?.There was no correlation between SUVmax,MTV,TLG of mediastinal lymph nodes and the length and diameter of primary focus of lung cancer.There was no correlation between MTV of mediastinal lymph nodes and SUVmax of primary focus of lung cancer.?P>0.05?4.In the malignant group of mediastinal lymph nodes,there were significant differences in SUVmax among different T stages,sites and pathological types of primary lung cancer?P<0.05?.Conclusion:1.SUVmax,SUVmean,MTV,TLG,short diameter,aspect ratio,SUVmax of SUVmax/mediastinal blood pool,necrosis,fat,calcification and symmetry of mediastinal lymph nodes are helpful to distinguish between benign and malignant mediastinal lymph nodes.2.The combination of MTV,SUVmax,aspect ratio and short diameter of mediastinal lymph nodes is helpful to distinguish benign from malignant lymph nodes more accurately.3.The SUVmax of primary lung cancer in NSCLC is helpful to distinguish between benign and malignant mediastinal lymph nodes.With the increase of primary SUVmax,the SUVmax of metastatic mediastinal lymph nodes increased and metastasized to the opposite side more easily.