title: An international confirmatory study of the prognostic value of early PET/CT in diffuse large B-cell lymphoma: comparison between Deauville criteria and ΔSUVmax.
abstract: OBJECTIVE
  The role of interim PET/CT in guiding therapeutic strategies in diffuse large B-cell lymphoma (DLBCL) is debated, mainly because interpretation rules vary among centres. This study aimed to explore the reproducibility and confirm the prognostic value of early PET/CT using the Deauville criteria and ΔSUVmax.
  
  
  METHODS
  This international confirmatory study retrospectively evaluated 114 patients with newly diagnosed DLBCL treated with a rituximab-containing regimen. All patients underwent ¹⁸F-FDG PET/CT at baseline (PET0) and after two cycles (PET2), with no therapy change based on the latter. Scans were interpreted by three observers using the Deauville five-point scale and ΔSUVmax between PET0 and PET2 was calculated. Interpretations were evaluated for interobserver agreement and for progression-free survival (PFS) prediction.
  
  
  RESULTS
  Median follow-up was 39 months. Early PET/CT was predictive of outcome when interpreted with the Deauville criteria and ΔSUVmax. Using the five-point scale, the overall kappa value was 0.66 with the reference background set in the liver (score ≥4) and interobserver agreement was even better using a 66% ΔSUVmax cut-off (κ = 0.83). Moreover, the prognostic value of interim PET was slightly inferior when using a Deauville score ≥4 than when using a 66% ΔSUVmax cut-off: for the Deauville score the 3-year PFS estimate was 59% (45-73%) in PET2-positive patients vs. 81% (71-91%) in PET2-negative patients (P = 0.003); for the 66% ΔSUVmax cut-off the 3-year PFS estimate was 44% (23-65%) in PET2-positive patients vs. 79% (70-88%) in PET2-negative patients (P = 0.0002).
  
  
  CONCLUSIONS
  Although the Deauville criteria are valid for assessing the prognostic value of early PET/CT in DLBCL, computation of the ΔSUVmax leads to better performance and interobserver reproducibility, and should be preferred when a baseline scan is available.
authors: Department of Nuclear Medicine, Henri Mondor Hospital and Paris-Est University, Créteil, France. emmanuel.itti@hmn.aphp.fr
authors: Emmanuel
authors: E
authors: Itti
authors: Michel
authors: M
authors: Meignan
authors: Alina
authors: A
authors: Berriolo-Riedinger
authors: Alberto
authors: A
authors: Biggi
authors: Amanda F
authors: AF
authors: Cashen
authors: Pierre
authors: P
authors: Véra
authors: Hervé
authors: H
authors: Tilly
authors: Barry A
authors: BA
authors: Siegel
authors: Andrea
authors: A
authors: Gallamini
authors: René-Olivier
authors: RO
authors: Casasnovas
authors: Corinne
authors: C
authors: Haioun
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003627:Data Interpretation, Statistical; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D015588:Observer Variation; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
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