Abstract P022

Association of Patlak-derived dynamic FDG PET parameters with Deauville response categories and kinetic heterogeneity of residual PET-positive findings in classical Hodgkin lymphoma: a prospective single-center pilot study

Background: FDG PET/CT interpreted using the Deauville score (DS) is the standard method for response assessment in classical Hodgkin lymphoma (cHL). However, visual assessment of residual uptake is limited by inflammatory changes and suboptimal specificity. Dynamic FDG PET/CT with Patlak kinetic modeling enables quantitative evaluation of tracer kinetics beyond SUV metrics.

Aim: To assess the association between Patlak-derived FDG PET parameters and Deauville response categories and to explore kinetic heterogeneity among residual PET-positive lesions in cHL.

Methods: In this prospective single-center pilot study, patients with cHL undergoing interim or end-of-treatment FDG PET/CT with residual uptake (Aug 2025–May 2026, University Hospital Olomouc) were included. Dynamic PET/CT was performed on a Siemens Biograph Vision 600 scanner. Patlak analysis with population-based input function was used to calculate metabolic rate of FDG (MRFDG) and distribution volume (DVFDG). One dominant mediastinal lesion per scan was analyzed. Scans were classified as PET-negative (DS 1–3) or PET-positive (DS 4–5). MRFDG and DVFDG were compared between groups; ROC analysis and intra-group variability were assessed.

Results: Fourteen examinations were included; 5 were DS 1–3 and 9 DS 4–5. MRFDG was higher in PET-positive vs PET-negative scans (12.34 ± 6.72 vs 4.59 ± 2.00; p= 0,009), with a 2.7-fold difference. DVFDG was also increased (208.83 ± 81.48 vs 110.95 ± 18.99; p=0.006). MRFDG and DVFDG showed strong discrimination (AUC 0.93 and 0.91, respectively). PET-positive scans showed marked heterogeneity in MRFDG (4.73–24.21) and DVFDG (105.84–389.39) despite identical DS.

Conclusions: Patlak-derived FDG PET parameters correlate with Deauville categories and reveal substantial kinetic heterogeneity among residual PET-positive cHL lesions. Dynamic PET may provide additional quantitative information beyond visual assessment. Further outcome-based validation is required.