Clinical Study On ～(18)F-FDG Imaging For Evaluation Of Response To Therapy And Prognosis In Non-Hodgkin's Lymphoma

Objective: (1) To evaluate the value of 18F-fluorodeoxyglucose (FDG) imaging for early evaluation of response to therapy and prediction of prognosis in non-Hodgkin's lymphoma (NHL). (2) To study the prognostic value of ¹⁸F-FDG imaging and CT before or after autologous stem cell transplantation (ASCT) for clinical outcome in NHL.Materials and methods:Part 1: 64 patients with pathologically confirmed NHL who had ¹⁸F-FDG imaging at baseline (initial scan) and after three to four cycles of chemotherapy (interim scan) were included. The patients were categorized into FDG negative (n=31) and positive (n=33) groups based on the interim FDG scanning results at the early stage after chemotherapy. We performed univariate survival analysis with Kaplan-Meier method. Mutivariate analysis was performed with the Cox proportional hazards model. The value of FDG interim scans was compared to CT.Part 2: A retrospective review of 17 NHL patients undergoing ¹⁸F-FDG imaging before or after ASCT was performed. Positive predictive value (PPV), negative predictive value (NPV) and accuracy were compared to the results of CT. The therapy response on FDG scans and CT were correlated to PFS using Kaplan-Meier survival analysis.Results:Part 1: In FDG negative group, 26 cases were in complete remission, 4 in partial remission and 1 in progression. In FDG positive group, there were 2 cases with complete remission and 14 with progression. Univariate survival analyses showed significant correlations of presence of extranodal disease, degree of malignancy, clinical disease stage, serum lactate dehydrogenase concentration and early interim FDG imaging with PFS (P<0.05). The estimated 2 year PFS rate was 68.4% and 18.2% in FDG negative and positive group, respectively. In the COX regression model, response on interim FDG imaging proved to be the strongest variables with independent prognostic value (P<0.001). In 52 NHL patients, results on interim FDG imaging (P<0.001) but not CT results (P>0.1) were strongly correlated with PFS. Part 2: PPV, NPV and accuracy were 78%, 71% and 75% for ¹⁸F-FDG imaging before ASCT and 86%, 63% and 73% for ¹⁸F-FDG imaging after ASCT. Results on ¹⁸F-FDG imaging before or after ASCT (P<0.05) but not CT results (P>0.05) were strongly correlated with PFS.Conclusion: (1) Early interim FDG imaging may be valuable in early assessment of response to chemotherapy. Early interim FDG imaging is an excellent and independent predictor of PFS in NHL, which is superior to CT in the prediction of prognosis. (2) ¹⁸F-FDG imaging before or after ASCT, which is superior to CT, can be used to predict the post-ASCT outcome of NHL patients.