Study Of ¹⁸F-FDG PET/CT In Predicting Interim Treatment Response And Prognosis Of Patients With Diffuse Large B-cell Lymphoma

Objective:To investigate the predictive value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography(¹⁸F-FDG PET/CT)quantitative parameters and texture parameters for interim treatment response and prognosis of patients with diffuse large B-cell lymphoma（DLBCL）receiving R-CHOP chemotherapy.Methods:PET/CT images and clinical data of patients with DLBCL who had undergone PET/CT scans before and after 3 to 4 cycles R-CHOP chemotherapy were reviewed.Baseline PET/CT parameters were measured and 12first-order textural features of PET images based on histogram analysis were extracted.（1）Baseline PET/CT parameters and clinical indicators were compared between CR group and Non-CR group groups based on interim treatment response.Receiver operating characteristic（ROC）curve analysis was performed to estimate optimal cutoff values and diagnostic efficacy of baseline PET/CT parameters with significant difference.Multivariate logistic regression analysis was performed to select independent predictive factors for interim treatment response.ROC curve analysis was performed to evaluate the efficiency of logistic regression model.（2）Univariate analysis was performed to evaluate the influence of baseline PET/CT parameters,clinical indicators and interim treatment response on prognosis.Cox multivariate regression analysis was performed with univariate indicators with significant difference.2-year PFS and OS were estimated using Kaplan-Meier method.ROC curve analysis was performed to estimate the efficacy of baseline PET/CT parameters,interim treatment response and combination of them for predicting prognosis.（3）PET texture parameters were compared between responding group and Non-responding group,CR group and Non-CR group,better prognosis group and worse prognosis group.PET texture parameters with significant difference were included in multivariate logistic regression analysis,and regression models were constructed.ROC curve analysis was performed to evaluate the diagnostic efficacy of models.Results:（1）MTVmax,MTVsum,TLGmax,TLGsum,Dmax,IPI,LDH,number of extranodal organ involvement and necrosis were significantly different between CR group and Non-CR group（P<0.05）.Optimal cutoff values for MTVmax,MTVsum,TLGmax,TLGsum and Dmax to predict interim treatment response were 57.2cm³,45.3cm³,756.0g,1977.1g and 6.6cm,and AUC of them were 0.693,0.708,0.707,0.698,0.717,respectively,and Dmax had the highest efficacy.Dmax and IPI were independent predictive indicators for interim treatment response.The AUC of logistic regression model Yˊ=0.499X₁+0.118X₂-2.436（X₁,X₂represent IPI and Dmax）was0.753.（2）Clinic staging,IPI,LDH,necrosis,MTVmax,TLGmax,Dmax and interim CR were associated with 2-year PFS.LDH,necrosis,MTVmax,MTVsum,TLGmax,TLGsum,Dmax and interim CR were associated with 2-year OS.Clinic staging,Dmax and interim treatment evaluation may be used as independent predictors of2-year PFS.Dmax and interim treatment response evaluation may be used as independent predictors of 2-year OS（P<0.05）.Kaplan-Meier curves of Dmax<5.7cm group and Dmax≥5.7cm group,CR group and Non-CR group were significantly different（P<0.05）.The AUC,sensitivity and specificity of the combination of Dmax and interim CR for predicting 2-year PFS were 0.801,73.9%and 92.7%,respectively,and the AUC,sensitivity and specificity for predicting 2-year OS were 0.689,76.5%and 76.6%,respectively.（3）Relative deviation,energy and entropy were statistically different between responding group and Non-responding group,CR group and Non-CR group,better prognosis group and worse prognosis group（P<0.05）.Relative deviation,energy and entropy were included in multivariate logistic regression analysis.Logistic regression models for predicting interim Non-response,Non-CR and worse prognosis were Y₁ˊ=-0.007X₁-66.678X₂-1.426X₃+7.565,Y₂ˊ=-0.003X₁+3.518X₂+0.393X₃-3.094,Y₃ˊ=-0.004X₁-55.582X₂-0.782X₃+5.020,X₁,X₂,X₃represent relative deviation,energy and entropy.The AUC of models were 0.73,0.71and 0.76,respectively.Conclusions:（1）Baseline PET/CT parameters may be used as predictive factors for interim treatment response in DLBCL patients treated with R-CHOP,and Dmax,IPI are independent predictive factors,which can provide important information for clinical treatment.（2）Baseline PET/CT parameters and interim treatment response evaluation has important prognostic value for patients with DLBCL receiving R-CHOP chemotherapy.Dmax and interim treatment response are independent predictive factors 2-year PFS and OS.The combination of them can improve the diagnostic efficiency of prognostication for 2-year PFS than single index.（3）PET texture parameters of baseline PET/CT have potential value in predicting interim treatment response and prognosis of the patients with DLBCL receiving R-CHOP chemotherapy.