Interobserver Variability and Diagnostic Performance in Predicting Malignancy of Pancreatic Intraductal Papillary Mucinous Neoplasm with MRI.

Background The 2017 international consensus guidelines for intraductal papillary mucinous neoplasm (IPMN) of the pancreas are widely used. Purpose To evaluate the interobserver agreement and diagnostic performance of MRI assessment in predicting the malignant potential of IPMN according to radiologists' experience. Materials and Methods This multicenter retrospective study included 100 patients with pathologically proven pancreatic IPMN (77 patients with surgery, 23 patients with biopsy) who underwent contrast-enhanced MRI between 2016 and 2021. Eight post-fellowship radiologists (four more-experienced [8-20 years] and four less-experienced [1-4 years] reviewers) evaluated MRI for high-risk stigmata and worrisome features identified by the most recent 2017 guidelines. Interobserver agreement was determined using Fleiss κ statistics according to radiologist experience. The diagnostic performance for malignant IPMN was assessed using receiver operating characteristic curve analysis. Results Among 100 patients (mean age, 66 years ± 10 [SD]; 57 men), 52 (52%) had malignant IPMN. For high-risk stigmata, interobserver agreement was substantial for main pancreatic duct size of at least 10 mm (κ = 0.78; 95% CI: 0.75, 0.82), enhancing mural nodule of at least 5 mm (κ = 0.70: 95% CI: 0.66, 0.74), and at least one high-risk stigmata (κ = 0.73: 95% CI: 0.69, 0.76). The worrisome features showed fair to substantial interobserver agreement (κ range, 0.22-0.80). More-experienced reviewers demonstrated better agreement in the assessment of at least one high-risk stigmata than less-experienced reviewers (κ = 0.77 vs κ = 0.69, < .001). The overall diagnostic performance of each reviewer was good for the prediction of malignant pancreatic IPMN (area under the receiver operating characteristic curve [AUC] range, 0.77-0.84; median AUC, 0.82), with substantial agreement (κ = 0.76). Conclusion The 2017 international consensus guidelines enabled good diagnostic performance and substantial interobserver agreement for high-risk stigmata but not worrisome features on the evaluation of the malignant pancreatic IPMN using MRI. Agreement tended to be better among more-experienced reviewers than among less-experienced reviewers. © RSNA, 2023