Diagnostic Performance of Node-RADS for CT-based Assessment of Regional Lymph Nodes in Pancreatic Ductal Adenocarcinoma

Objectives To investigate the diagnostic performance of Node Reporting and Data System (Node-RADS) for regional lymph node staging in pancreatic ductal adenocarcinoma (PDAC), using histopathology as reference standard, and to compare Node-RADS with individual size- and morphology-based criteria. Methods This retrospective multicenter study included 87 consecutive patients (median age, 72 years, range 43–91 years; 45 women) with histologically confirmed PDAC and preoperative CT. Two blinded readers independently assessed regional lymph nodes and assigned Node-RADS scores. Diagnostic performance (sensitivity, specificity, Youden’s index, area under the receiver operating characteristic curve (AUROC) for numeric size and Node-RADS) and interreader agreement (Cohen’s κ) were calculated. Results Eighty-seven patients were included (median age 72 years); 54/87 (62.1%) were node-positive. Overall, 257 regional lymph nodes were assessed on CT (median, 3 per patient), compared with a median of 16 lymph nodes per patient evaluated by histopathology. Node-RADS showed poor discrimination and did not outperform short-axis size (AUROC 0.58, CI 0.45–0.70 vs. 0.56, CI 0.43–0.68; p = 0.70). The PDAC-recommended threshold (Node-RADS ≥ 3) yielded 24.1% sensitivity and 81.8% specificity (Youden’s index 0.06). The best-performing size cutoff was short-axis ≥ 10 mm (sensitivity 25.9%, specificity 84.8%, Youden’s index 0.11). Individual morphologic features were specific but infrequent, resulting in low sensitivity. Interreader agreement was slight to substantial for size thresholds (κ = 0.32–0.65) but slight for Node-RADS (κ = 0.07 for ≥ 3) and most configuration features. Conclusion Node-RADS provides limited accuracy and low reproducibility for regional lymph node staging in PDAC and does not improve upon conventional size- or morphology-based criteria.