The prognostic value of interim positron emission tomography (PET) interpreted according to visual criteria is a matter of debate in diffuse large B-cell lymphoma (DLBCL). Maximal standardized uptake value reduction (⌬SUVmax) may better predict outcome. To compare the prognostic value of both methods, we analyzed PET done at baseline (PET0) and after 2 (PET2) and 4 (PET4) cycles in 85 patients with high-risk DLBCL enrolled on a prospective multicenter trial. All images were centrally reviewed and interpreted visually according to the International Harmonization Project criteria and by computing ⌬SUVmax between PET0 and PET2 (⌬SUVmaxPET0-2) or PET4 (⌬SUVmaxPET0-4). Optimal cutoff to predict progression or death was 66% for ⌬SUVmaxPET0-2 and 70% for ⌬SUVmaxPET0-4. Outcomes did not differ significantly whether PET2 and PET4 were visually positive or negative. Inversely, ⌬SUVmaxPET0-2 analysis (> 66% vs < 66%) identified patients with significantly different 2-year progression-free survival (77% vs 57%; P ‫؍‬ .0282) and overall survival (93% vs 60%; P < .0001). ⌬SUVmaxPET0-4 analysis (> 70% vs < 70%) seemed even more predictive for 2-year progression-free survival (83 vs 40%; P < .0001) and overall survival (94% vs 50%; P < .0001). ⌬SUVmax analysis of sequential interim PET is feasible for highrisk DLBCL and better predicts outcome than visual analysis. The trial was registered at http://clinicaltrials.gov as NCT00498043. (Blood. 2011;118(1):37-43)

PET performed either after four cycles of R-CHOP or at the end of therapy was strongly predictive of outcome in this prospective study. Therapeutic intervention based on PET results during or after inductive treatment should be evaluated.

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Fluorodeoxyglucose positron emission tomography failed to detect distant metastases at initial staging in patients with a positive SLNB, even in patients who presented with distant metastases within 12 months after the FDG PET scan. These results could be explained by the low prevalence of macroscopic metastatic disease at this stage and by the important delay between the onset of the spread of microscopic metastatic disease and the identification by PET scan of macroscopic metastatic disease.

PET/CT negativity before ASCT is a desirable and achievable goal in the management of chemosensitive FL relapsing after first-line R-CHOP.