Standardized visual reading of F18-FDG-PET in patients with non-small cell lung cancer scheduled for preoperative thoracic lymph node staging.

Abstract Objectives Routine visual assessment of positron emission tomography (PET) for thoracic lymph node (LN) staging in patients with non-small cell lung cancer (NSCLC) is limited by a lack of reliable assessment criteria. This study evaluates the accuracy and inter-rater agreement of a standardized approach with unified windowing and a PET-based visual score. Materials and methods This retrospective analysis included pretherapeutic FDG-PET data of 86 patients with NSCLC. After standardized windowing (threshold: 2 × liver SUVmean) the LN uptake was assessed visually by three independent readers with varying levels of experience using a 4-step score (1, LN uptake ≤ mediastinal blood pool structures (MBPS); 2, MBPS  Results Fifty-four of the 278 LNs (19.4%) were malignant (optimal cut-off to differentiate benign vs. malignant, score >3). The inexperienced (n = 1), advanced (n = 1), and expert readers (n = 1) achieved similar accuracies of 93.5%, 91.4% and 92.1%, respectively ( P  > 0.05 each). Cohen’s κ ranged from 0.92 to 0.96 and Fleiss’ κ was 0.93. ROC-analyses showed no significant differences between attendant readers within any subgroup (AUC, 0.92–0.96). Conclusion Applying unified windowing, the introduced PET-score achieved highly accurate and robust LN assessment. This approach may shorten learning curves of inexperienced readers, facilitate multicenter trials, and improve comparability of future studies.