Inter-Reader Reliability of Early FDG-PET/CT Response Assessment Using the Deauville Scale after 2 Cycles of Intensive Chemotherapy (OEPA) in Hodgkin's Lymphoma

Abstract

Purpose: The five point Deauville (D) scale is widely used to assess interim PET metabolic response to chemotherapy in Hodgkin lymphoma (HL) patients. An International Validation Study reported good concordance among reviewers in ABVD treated advanced stage HL patients for the binary discrimination between score D1,2,3 and score D4,5. Inter-reader reliability of the whole scale is not well characterised.

Methods: Five international expert readers scored 100 interim PET/CT scans from paediatric HL patients. Scans were acquired in 51 European hospitals after two courses of OEPA chemotherapy (according to the EuroNet-PHL-C1 study). Images were interpreted in direct comparison with staging PET/CTs.

Results: The probability that two random readers concord on the five point D score of a random case is only 42% (global kappa = 0.24). Aggregating to a three point scale D1,2 vs. D3 vs. D4,5 improves concordance to 60% (kappa = 0.34). Concordance if one of two readers assigns a given score is 70% for score D1,2 only 36% for score D3 and 64% for D4,5. Concordance for the binary decisions D1,2 vs. D3,4,5 is 67% and 86% for D1,2,3 vs D4,5 (kappa = 0.36 resp. 0.56). If one reader assigns D1,2,3 concordance probability is 92%, but only 64% if D4,5 is called. Discrepancies occur mainly in mediastinum, neck and skeleton.

Conclusion: Inter-reader reliability of the five point D-scale is poor in this interobserver analysis of paediatric patients who underwent OEPA. Inter-reader variability is maximal in cases assigned to D2 or D3. The binary distinction D1,2,3 versus D4,5 is the most reliable criterion for clinical decision making.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Discrepant D scoring of the right supraclavicular region.

Case 63. a) Tumour involvement before treatment. b) Residual mass in this region after two cycles of OEPA. c) and d) slightly enhanced FDG uptake above background in this area. Interpretation might be complicated by a slightly enhanced FDG uptake symmetrically in the left supraclavicular area which, however, is in the surrounding of a catheter and by the inhomogeneous uptake in the mediastinum. Deauville score of the readers R1-5, respectively: 1-1-3-1-2. Courtesy Dept. Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.

Fig 2. Residual uptake in the mediastinum vs. thymus.

Case 12: a) Lymphoma involvement of the upper and middle mediastinum including the thymus before treatment. b) and c) very slightly enhanced uptake as compared to the mediastinum after two cycles ChT. The interpretation might be complicated by the difficult decision whether this finding implies residual tumor uptake or physiological but inhomogeneous uptake in the thymus. Deauville score of the readers R1-5, respectively: 1-1-3-3-3. Courtesy Dept. Nuclear Medicine, Blackrock Clinic, Dublin, Ireland.

Fig 3. Discrepant D scoring of the neck region.

Case 44: a) Lymphoma involvement at both sides of the neck before treatment. b) and c) residual lymph node on the right neck with slightly enhanced FDG uptake after to cycles ChT. d) The residual uptake is less than in the liver, but it is difficult to decide if it is above or below the MBP uptake. Deauville score of the readers R1-5, respectively: 2-3-3-1-3. Courtesy Dept. Clinical Physiology, Sahlgrenska University Hospital, Gothenburg Sweden.

Fig 4. Discrepant D scoring of the mediastinum.

Case 39: a) extensive lymphoma involvement of the left side of the upper mediastinum before treatment. b) residual mass after two cycles ChT. c) highest residual FDG uptake in the dorsal part of the residuum. D) It is difficult to decide if this highest FDG uptake is above or below the liver uptake. The interpretation is complicated by the small size of the hottest part of the residuum. Deauville score of the readers R1-5, respectively: 3-3-4-4-4. Courtesy M. Reinhardt, Dept. Nuclear Medicine, Pius-Hospital, Oldenburg, Germany.

Fig 5. Discrepant D scoring of the right supraclavicular region.

Case 2.: a) extensive lymphoma involvement including the right supraclavicular region before treatment. b—d) enhanced FDG uptake in a right supraclavicular node clearly exceeding that of the mediastinum. It is difficult to decide if the nodal uptake is higher or less than the liver uptake. Deauville score of the readers R1-5 for the supraclavicular region, respectively: 3-4-3-3-4. Courtesy Dept. Nuclear Medicine, University Hospital Erlangen, Germany.