Page 16 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

Chapter 1
Table 1. Deauville 5-point scale (based on [18F]FDG avidity during and after treatment)
Deauville score
1 2 3 4 5 X
Interpretation*
No uptake
Uptake ≤ mediastinum
Uptake > mediastinum but ≤ liver
Uptake moderately^ higher than liver
Uptake markedly^ higher than liver and/or new lesions New areas of uptake unlikely to be related to lymphoma
*The Deauville 5-point scale scores the most intense uptake in a site of initial disease
^The consensus guideline suggests that Deauville score 4 should be applied to uptake > the maximum SUV in a large region of normal liver and Deauville score 5 to uptake 2x to 3x > the maximum SUV in the liver [22].
Semi-quantitative methods
Standardized uptake value (SUV) quantifies the level of [18F]FDG uptake in a lesion normalized for the injected [18F]FDG activity and volume of distribution (e.g. body weight). With an [18F]FDG PET scan being intrinsically a quantitative imaging method, it seems logical to assess therapy response by determination of the SUV and change of SUV (∆SUV).To date most studies apply the SUVmax metrics (i.e. reflecting the [18F]FDG uptake in the voxel with the highest [18F]FDG uptake in a lesion). For lymphomas a rapid drop in SUVmax is common, reported cut‐offs for a clinically relevant interim [18F]FDG PET response assessment in DLBCL ranged from 66% to 73% [33-35]. In a retrospective validation study in 114 DLBCL patients it was concluded that both Deauville and ∆SUVmax criteria for interim [18F]FDG PET assessment after 2 cycles of chemotherapy were valid for progression-free survival outcome prediction [36]. There was a better performance and interobserver reproducibility for ∆SUVmax, however the requirement of a baseline [18F]FDG PET is obvious to allow a ∆SUVmax analysis [36]. Residual questions are which criteria best predict the 2-years progression- free survival and whether these criteria can be validated in other DLBCL cohorts.
Timing of interim [18F]FDG PET
At any observation time during first-line chemotherapy, [18F]FDG uptake reflects a dynamic metabolic state, that is a balance between tumor growth, death of chemosensitive tumor components and later regrowth of chemoresistant
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