APPLICATION OF THE LUGANO CLASSIFICATION FOR INITIAL EVALUATION, STAGING, AND RESPONSE ASSESSMENT OF HODGKIN AND NON-HODGKIN LYMPHOMA: THE PROLOG CONSENSUS INITIATIVE (PART 1- CLINICAL).

Rationale: To provide consensus recommendations from a consortium of academic and industry experts in the field of lymphoma and imaging for the consistent application of the Lugano classification. Methods: Consensus was obtained through a series of meetings from July 2019 until July 2021 sponsored by the PINTaD (Pharma Imaging Network for Therapeutics and Diagnostics) as part of the ProLoG consensus initiative. Results: Consensus recommendations clarified technical considerations for PET-CT and diagnostic CT from the Lugano Classification including updating the FDG-avidity of different lymphoma entities, clarifying the response nomenclature and refining lesion classification and scoring, especially with regards to scores 4 and 5 and the X category of the 5 point scale. Combination of metabolic and anatomic responses is clarified and response assessment in case of discordant or missing evaluations. Usage of clinical data in the classification, especially the requirement for bone marrow assessment is further updated based on lymphoma entities. Clarification is provided with regards to spleen and liver measurements and evaluation, as well as nodal response. Conclusion: Consensus recommendations are made to comprehensively address areas of inconsistency and ambiguity in the classification encountered during response evaluation by end users and such guidance should be used as a companion to the Lugano 2014.