An improved diagnostic criterion based on Node-RADS MRI score for lymph node metastasis in papillary thyroid carcinoma.

Background: Accurate preoperative diagnosis of lymph node (LN) metastasis in papillary thyroid carcinoma (PTC) remains challenging. This study aimed to evaluate the diagnostic performance of Node Reporting and Data System (Node-RADS) magnetic resonance imaging (MRI) score for detecting LN metastasis in PTC and to investigate whether a novel diagnostic criterion incorporating Node-RADS with supplementary MRI features could improve diagnostic accuracy. Methods: In this prospective study, 82 consecutive PTC patients with 156 histopathologically confirmed LNs were enrolled. Node-RADS and supplementary MRI features were evaluated by three radiologists independently. A new diagnostic criterion was further developed by combining Node-RADS and significant supplementary MRI features. Univariate and multivariate logistic regressions identified potential predictors of metastasis. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. Receiver operating characteristic (ROC) curve analysis, with the area under the curve (AUC), was performed to evaluate diagnostic effectiveness. Results: Node-RADS demonstrated the highest performance (sensitivity 80.7%; specificity 74.5%; AUC =0.776) in diagnosing LN metastasis in PTC when applying a Node-RADS ≥3 criterion, in comparison to Node-RADS ≥4 (sensitivity 51.4%; specificity 89.4%; AUC =0.704; P=0.034) and Node-RADS ≥5 (sensitivity 21.2%; specificity 95.7%; AUC =0.584; P<0.001). Node-RADS and T1 hyperintensity were independent predictors of metastasis on multivariate analysis. Node-RADS combined with T1 hyperintensity showed a better diagnostic performance (sensitivity 75.2%; specificity 87.2%; AUC =0.856) than Node-RADS alone. Conclusions: The new MRI-based diagnostic criterion incorporating Node-RADS and T1 hyperintensity demonstrates improved performance for diagnosing LN metastasis in PTC compared to Node-RADS.