PURPOSE: Total metabolic tumor volume (TMTV) at baseline becomes a key biomarker in several lymphoma subtypes. Variability in segmentation methods such as 41%SUVmax and SUVmax >
4 has limited its clinical application. Additionally, immune-checkpoint-inhibitors introduced challenges in response assessment due to pseudoprogression, complicating the use of traditional metrics. This study investigates the prognostic impact of baseline- and residual-TMTV and introduces a novel personalized-liver-based-threshold (pTMTV METHODS: We analyzed 91 patients with relapsed/refractory diffuse-large-B-cell lymphoma and follicular lymphoma from the GATA trial, comparing patient's outcome according to three segmentation methods: TMTV RESULTS: Baseline-TMTV significantly influenced prognosis with higher TMTV correlating with shorter PFS and OS (p <
0.0001 for all methods). Residual-TMTV, particularly with pTMTV CONCLUSION: Baseline- and residual-TMTV strongly influence prognosis and response in lymphoma patients. The novel personalized pTMTV