SUVmax Ratio Of Mediastinal Lymph Node To Primary Tumor And To Liver In Dignosis Of Mediastinal Lymph Node Metastasis In Patients With Non-Small Cell Lung Cancer

Background and objectiveLung cancer is one of the most common malignant tumor in the world which is the most frequent leading cause of cancer-related deaths. PET/CT paly an important role in staging of lung cancer, previous use of the maximum standardized uptake value(SUVmax) as PET/CT semi-quantitative indicators to determine whether the mediastinal lymph node metastasis. This study focused on the prognostic value of SUVmax ratio of mediastinal lymph node to primary tumor and lymph node to liver in dignosis of mediastinal lymph node metastasis in patients with non-small cell lung cancer(NSCLC). Materials and Methods103 cases NSCLC patients were collected from January 2011 to January 2014 which were identified pathologically, all these patients were underwent 18F-FDG PET/CT Scanning two weeks before the operation., and any anti-tumor therapy was not carried out before PET/CT imaging.All these patients were analyzed by visual method and semi-quantitative method. The SUVmax of primary tumors, mediastinal lymph nodes and liver were measured respectively, and then the ratio of lymph node/primary tumor SUVmax and lymph node/liver SUVmax were calculated, mediastinal lymph nodes were divided into metastatic group and non-metastatic group as the standard of the postoperative pathology results.Using SPSS 17.0 software for statistical analysis. The differences of lymph node SUVmax, lymph node/primary tumor SUVmax and lymph node/liver SUVmax between metastasis and non-metastatic group were compared by Independent Samples t test, P <0.05 was considered statistically significant; the best diagnostic cut-off value to diagnosing mediastinal lymph node metastasis of lymph node SUVmax, lymph node/primary SUVmax and lymph node/liver SUVmax were confirmed by ROC curves; The differences of sensitivity, specificity and accuracy with the best diagnostic cut-off value to diagnosing mediastinal lymph node metastasis of lymph node SUVmax, lymph node/primary SUVmax and lymph node/liver SUVmax by c2 test, the test level for P <0.05. ResultsLymph node SUVmax, lymph node/primary tumor SUVmax and lymph node/liver SUVmax of metastatic group(averages were 6.71 ± 5.28,0.55 ± 0.39 and 2.13 ± 1.96) were higher than non-metastatic group(averages were 2.53 ± 0.80,0.20 ± 0.10 and 0.78 ± 0.27). Differences were statistically significant(P <0.05)The best diagnostic cutoff value of lymph SUVmax, lymph node/primary tumor SUVmax and lymph node/liver SUVmax respectively were SUVmax≥4.38, lymph node/primary tumor SUVmax≥0.25, lymph node/liver SUVmax≥1.27, and corresponding the area under the ROC curve respectively were 0.799,0.849 and 0.790.The sensitivity, specificity and accuracy of lymph SUVmax≥4.38 were 55.29%, 97.32% and 86.99%; lymph node/primary tumor SUVmax≥0.25 were 72.94%, 79.31% and 77.75%; lymph node/liver SUVmax≥1.27 were 57.65%, 95.40% and 86.13%.The specificity and accuracy of diagnosing mediastinal lymph node metastasis with lymph node/primary tumor SUVmax≥0.25 were higher than SUVmax≥2.50, the differences were statistically significant(c2 = 29.04,22.16, P <0.05). The specificity and accuracy of diagnosing mediastinal lymph node metastasis with lymph node/liver SUVmax≥1.27 were higher than SUVmax≥2.50, the differences were statistically significant(c2 = 98.00 and 57.05, P <0.05). The sensitivity of diagnosing mediastinal lymph node metastasis with lymph node/primary tumor SUVmax≥0.25 higher than SUVmax≥4.38, while the specificity and accuracy of diagnosing mediastinal lymph node metastasis with lymph node/primary tumor SUVmax≥0.25 lower than SUVmax≥4.38, the differences were statistically significant(c2= 13.07,46.02,17.29, P <0.05). The sensitivity of diagnosing mediastinal lymph node metastasis with lymph node/primary tumor SUVmax≥0.25 higher than SUVmax≥1.27, while the specificity and accuracy of diagnosing mediastinal lymph node metastasis with lymph node/primary tumor SUVmax≥0.25 lower than lymph node/liver SUVmax≥1.27, the differences were statistically significant(c2 = 11.08,32.67,12.55, P <0.05). The differences of sensitivity, specificity and accuracy of diagnosing mediastinal lymph node metastasis with lymph node/liver SUVmax≥1.27 and SUVmax≥4.38 showed no significant difference(c2 = 0.50,3.20,0.57, P> 0.05). ConclusionThe SUVmax ratio of mediastinal lymph node to primary tumor and lymph node to liver as an new semi-quantitative parameters for dignosing mediastinal lymph node metastasis in patients with non-small cell lung cancer. For patients with different conditions, with a variety of semi-quantitative parameters, mediastinal lymph nodes may be more accurate staging.