Page 15 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

The value of [18F]FDG PET as a tool for interim response assessment in DLBCL is still highly debated. Observational studies have indicated that interim [18F] FDG PET may be predictive, but the results reveal inconsistencies and clinical heterogeneity [26]. It is unclear to which extent these inconsistencies are due to differences in the timing of PET during therapy and/or different PET positivity criteria or clinical heterogeneity resulting from studies including patients with different prognostic characteristics. So far these inconsistencies and heterogeneity preclude the standard use of interim [18F]FDG PET for DLBCL in daily clinical practice.
PET response criteria for interim and end-of-treatment [18F]FDG PET
In literature 2 types of [18F]FDG PET response assessment are currently used in lymphoma:
1. Visual (qualitative) methods.
2. SUV-based (standardized uptake value, semi-quantitative) methods.
Visual methods
In clinical practice [18F]FDG PET scans are typically interpreted visually. The question arose whether the IHP criteria for end-of-treatment response assessment [20] could also be used for interim [18F]FDG PET response assessment. It was hypothesized that a more liberal [27] or higher cut-off (liver instead of mediastinal blood pool) is needed for this earlier response assessment [28]. A systematic review from 2009 reported that various definitions for positive and negative diagnostic criteria were used for interim [18F]FDG PET [26]. The need for uniform and flexible criteria led to the introduction of a 5-point scale.This system was originally developed in London [29,30], but later called Deauville criteria [31,32], because of the adoption of these criteria during the first lymphoma consensus workshop in Deauville. The Deauville criteria (Table 1) use the mediastinal blood pool and liver as reference for tumor uptake, and are the recommended response evaluation criteria for both interim- and end-of-treatment [18F]FDG PET in the Lugano classification guidelines [22,23].
General introduction
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