Evaluating ΔMTV%, ΔDmax%, and %ΔSUVmax of 18F-FDG PET/CT for mid-treatment efficacy and prognosis in diffuse large B-cell lymphoma

Purpose To investigate the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging in interim therapeutic and prognostic evaluation of patients with diffuse large B-cell lymphoma (DLBCL). Materials and methods Data of 86 patients with pathologically confirmed DLBCL who underwent F-18-FDG PET/CT imaging before chemotherapy, radiotherapy, and after interim chemotherapy, were retrospectively analyzed. Receive operating characteristic (ROC) curve analysis was performed to assess the predictive capacity of changes and change rates in PET/CT imaging parameters [maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum tumor dissemination (D-max)] for progression-free survival (PFS) and to identify optimal cutoff values. Kaplan-Meier survival curves were constructed, and the log-rank test was used to assess intergroup differences. Cox regression analysis was used to explore potential factors influencing PFS. Results Among 86 patients [(45 men, 41 women, age: 57.8 +/- 12.2 years)], the median PFS was 22.5 (14.5, 46) months. Until the last follow-up date, progression or recurrence occurred in 14 patients, while 9 patients died. The ROC curves indicated that the optimal cutoff values for predicting PFS were 99.10%, 99.72%, and 96.47% for Delta MTV%, Delta TLG%, and Delta D-max%, respectively (area under the curve = 0.786-0.849, all P < 0.05). Cox univariate analysis demonstrated that the alteration rates in metabolic and diffusion parameters before and after treatment, including SUVmax%, MTV%, TLG%, and D-max%, were predictive of PFS (hazard ratio [HR] = 6.213-13.430, all P < 0.05). The Cox multivariate analysis demonstrated that Delta MTV% and Delta D-max% independently predicted PFS, with HRs of 10.727 (95% confidence interval [CI] = 1.928-56.672, P = 0.007) and 7.178 (95%CI = 1.514-34.041, P = 0.013), respectively. We established a new prediction model by combining the Delta MTV% and Delta D-max% parameters, and the results of the model showed statistically significant differences in PFS between the high, intermediate, and low-risk groups. The model predicted higher effects than individual indicators. Conclusion The rate of change in metabolic and diffusion parameters on interim PET/CT can predict the prognosis of patients with DLBCL.