Prognostic Impact of Quantitative Changes Between Baseline and Interim 18F-FDG PET/CT in Pediatric Classic Hodgkin Lymphoma

Purpose: 18 F-FDG PET/CT plays a crucial role in the evaluation and management of pediatric classic Hodgkin lymphoma (cHL). In addition to visual assessment, quantitative parameters also have prognostic value. This study aimed to investigate the prognostic significance of PET parameters, with a particular focus on the changes observed in these parameters after 2 cycles of chemotherapy, in pediatric cHL patients. Patients and Methods: The study was designed as a single-center, retrospective. A total of 198 pediatric cHL patients who underwent baseline and post-2-cycle chemotherapy interim 18 F-FDG PET/CT imaging between January 2019 and October 2023 were included in the study. Four different segmentation methods (%41 SUVmax, %42 SUVmax, mediastinal SUVmax, and liver SUVmax) were applied. Quantitative parameters, including metabolic tumor volume (MTV), total lesion glycolysis (TLG), and their changes after 2 chemotherapy cycles (ΔMTV, ΔTLG), were evaluated for each segmentation method. The prognostic significance of these parameters for progression-free survival (PFS) was assessed using Cox regression analysis, while survival differences based on optimal cutoff values were evaluated using Kaplan-Meier analysis. Results: A total of 48 pediatric cHL patients (32 males, median age: 12 y) met the inclusion criteria. During a median follow-up of 21 months (range: 5–52 mo), disease progression was observed in 22.9% of the patients (n=11). Baseline 18 F-FDG PET/CT quantitative parameters did not show significant differences between progression and nonprogression groups. However, on interim 18 F-FDG PET/CT, higher values of quantitative parameters from 3 segmentation methods (%41 SUVmax, %42 SUVmax, and mediastinal SUVmax) and lower postchemotherapy reductions in ΔSUVmax, ΔMTV (41) , ΔMTV (42) , ΔTLG (41) , and ΔTLG (med) were associated with poor PFS. In multivariate Cox regression analysis, i-SUVmax (Hazard ratio, HR: 1.20, P <0.001) and ΔMTV (41) (HR: 0.965, P =0.007) were identified as independent risk factors for PFS. Conclusions: Interim 18 F-FDG PET parameters and postchemotherapy changes demonstrated significant prognostic value. Quantitative evaluation beyond visual assessment may contribute to risk-adapted and personalized treatment approaches in pediatric cHL.