Page 88 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

Chapter 4
For ordinal DSs, the reviewers agreed in 220 of 457 cases (Supplemental Table 2), resulting in a percentage of exact agreement of 48.1% (95%CI, 43.4–52.8). Percentage agreement was 83.4% (95%CI, 79.8–86.9) when we allowed a 1-point difference— except for a discrepancy between scores 3 and 4— between the reviewers’ scorings.
Supplemental Table 3 presents the percentage OA of the specific nodal and extranodal locations for dichotomized DS, related to the baseline prevalence. Gastrointestinal, skeletal, and mesenteric sites relatively showed the greatest number of discrepancies. Observer variation at EoT-PET in spleen and Waldeyer’s ring was less than at I-PET.
Comparison I-PET and EoT-PET Interobserver Agreement
PA did not significantly differ between I-PET and EoT-PET assessments (P = 0.656), but percentage OA was lower for I-PET (87.7% vs. 91.7%, respectively, P = 0.049), and there was a trend toward lower NA (92.0% vs. 95.0%, respectively, P = 0.091).
Figure 2. Example of discrepancy between reviewers’ assessment of skeletal lesion on, from left to right, axial attenuation-corrected PET, low-dose CT, and fused PET/CT images.
(A) Baseline 18F-FDG PET/CT with skeletal lesion in left acetabulum. (B) I-PET/CT after 4 cycles of R-CHOP14 showing rim of uptake scored by one reviewer as DS 4 and by other reviewer as unclear. (C) EoT-PET/CT after 8 cycles of R-CHOP14 showing residual uptake scores by one reviewer as DS 4 and by other reviewer as unclear.
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