¹⁸F-FDG PET/CT In Dignosis Of Mediastinal Lymph Node Metastasis In Patients Of Non-small Cell Lung Cancer

Objective:This study was to the diagnostic value of parameters related to¹⁸F-fluorodeoxyglucose-positron emission tomography(¹⁸F-FDG PET/CT)in diagnosis of mediastinal lymph node metastasis in patients of non-small cell lung cancer?NSCLC?.Materials and Methods:From December 2016 to December 2018,patients who under went PET/CT within 2 weeks before radical surgery and systemic mediastinal lymph node dissection surgery in affiliated hospital of Qingdao university were included.The results of PET/CT were compared with pathological results.All patients were analyzed by quantitative method,lymph node short diameter,CT value,maximum standardized uptake value(SUV_max),primary tumor SUV_max,mean standardized uptake value(SUV_mean)of liver,SUV_meanean of mediastinal blood pool were measured respectively,lymph node SUV_max/primary tumor SUVmax(SUV_n/t),lymph node SUV_max/liver SUV_mean(SUV_n/l)lymph node SUVmax/mediastinal blood pool SUV_mean(SUV_n/b)were calculated respectively.The difference of SUV_max,short diameter,CT value,SUV_n/t,SUV_n/l,and SUV_n/b/b between the metastatic and non-metastatic lymph nodes was compared by t-test or Mann-Whitney U test.Optimal cut-off values to diagnosis metastatic mediastinal lymph nodes were obtained by the receiver operating characteristic?ROC?curve.And the diagnostic efficacy of each parameter was compared the sensitivity and specificity corresponding to the critical value were obtained.The test level for p<0.05.Results:Among 110 patients with NSCLC,there were 75 cases of adenocarcinoma,32cases of squamous cell carcinoma,1 case of adenosquamous carcinoma,and 1 case of large cell neuroendocrine carcinoma.102 metastatic lymph nodes were found and 112lymph nodes were not metastasized.For all patients,there were significant differences in SUV_max?u value:2182.5,p<0.0001?,short diameter?u value:3428.5,p<0.0001?,SUV_n/t?u value:4136.5,p<0.0001?,SUV_n/l?u value:2650.0,p<0.0001?,and SUV_n/b?u value:p<0.0001?between the metastatic and non-metastatic groups.There was no significant difference in CT value between the metastatic and non-metastatic groups?u value:5163.5,p=0.225?.The optimal cut-off value for lymph node metastasis of lymph node SUV_maxax was 3.5,the sensitivity and specificity were 69.6%and 83.9%,and area under the curve?AUC?was 0.809,the optimal cut-off value of lymph node short diameter was 9.2mm,sensitivity and specificity were 49.0%and 82.1%,and AUC was0.700,the optimal cut-off value of SUV_n/t,SUV_n/l,SUV_n/b/b were 0.32,2.29,3.50,and the sensitivity were 75.5%,53.9%and 53.9%,the specificity were 54.5%,92.0%and 90.2%,AUC respectively were 0.638,0.768 and 0.768.For patients with lung adenocarcinoma,the difference in SUV_max,short diameter,SUV_n/l,and SUV_n/b/b between the metastatic and non-metastatic groups was statistically significant?both p<0.0001?,while there was no significant difference in CT value?u value:2314.0,p>0.05?and SUV_n/t?u value:2482.5,p>0.05?.The SUV_maxax of lymph node,lymph node short diameter,SUV_n/l,SUV_n/b/b optimal cut-off values were 3.3,8.9 mm,2.27 and 2.67,respectively,and the sensitivity were67.6%,46.0%,47.3%and 63.5%,the specificity were 84.7%,83.3%,90.3%and 76.4%,the AUC respectively were 0.802,0.681,0.730,0.736.For patients with squamous cell lung carcinoma,the difference in SUVmax,lymph node short diameter,SUV_n/t,SUV_n/l,and SUV_n/b/b between the metastatic and non-metastatic groups was statistically significant?both p<0.0001?,while the CT value was not statistically significant?u value:425.0,p=0.916?.The SUV_max,lymph node short diameter,SUV_n/t,SUV_n/l,and SUV_n/b/b optimal cut-off value for lymph node metastasis were 3.9,10 mm,0.31,2.29,and 3.55,respectively,and the sensitivity were 79.2%,62.5%,91.7%,75.0%and 75.0%,the specificity were 91.7%,88.9%,77.8%,97.2%and 91.7%.The AUC respectively were0.883,0.803,0.890,0.902,and 0.891.Conclusion:Parameters measured by ¹⁸F-FDG PET/CT such as lymph node SUV_max,short diameter,SUV_n/t,SUV_n/l,SUV_n/b/b were valuable for diagnosing lymph node metastasis,in which SUV_maxax is superior to other parameters,The cut-off value of SUV_maxax was 3.5.For patients with lung adenocarcinoma,the SUV_maxax of lymph nodes was still the most meaningful semi-quantitative parameter to distinguish metastatic and non-metastatics,which the cut-off value was 3.3.And for patients with lung squamous cell carcinoma,The cut-off value of SUV_maxax was 3.9,the diagnostic value of SUV_n/l was better.