Diagnostic performance of magnetic resonance image for malignant intraductal papillary mucinous neoplasms: the importance of size of enhancing mural nodule within cyst

To investigate the clinical significance of enhancing mural nodules ≥ 5 mm by comparing the diagnostic performance of high-risk stigmata for diagnosing the malignant IPMN between the international consensus guideline (ICG) 2012 and 2017 in pancreatic magnetic resonance image (MRI).In this retrospective study, we reviewed preoperative pancreatic MRI with surgically confirmed IPMNs between May 2009 and April 2021. High-risk stigmata, defined by ICG 2012 and ICG 2017, associated with malignant IPMN were evaluated using logistic regression analysis. We calculated and compared the sensitivity and specificity of ICG 2012 and ICG 2017 for diagnosing malignant IPMNs. Receiver-operating characteristic (ROC) curves were used to compare ICG 2012 to ICG 2017.A total of 73 patients (43 men and 30 women; mean age, 69 years; standard deviation, 8 years) with 34 malignant IPMNs and 39 benign IPMNs were included. Among high-risk stigmata, enhancing mural nodule ≥ 5 mm, and MPD diameter ≥ 10 mm were the significant predictor of malignant IPMN, in multivariate logistic regression (P 0.001 for all). For the diagnosis of malignant IPMN, the specificity of ICG 2017 for enhancing mural nodules ≥ 5 mm as the high-risk stigmata was significantly higher than that of ICG 2012 (87.2% vs. 64.1%, P = 0.008). However, there was no significant difference in sensitivity between the two guidelines (94.1% vs. 97.1%, P = 1.0). The comparison of the ROC curves showed that the diagnostic performance of ICG 2017 for malignant IPMNs (AUC, 0.91) significantly improved when compared to that of ICG 2012 (AUC, 0.81) (P = 0.01).When applying enhancing mural nodule ≥ 5 mm as a high-risk stigmata, ICG 2017 provided a significantly higher specificity than ICG 2012 without a reduction in sensitivity.