Quantitative Permeability MRI for Preoperative Differentiation of Warthin Tumors and Malignant Salivary Gland Lesions

Background/Objectives: Preoperative characterization of salivary gland tumors remains challenging because conventional MRI and diffusion-weighted imaging may show overlapping features, particularly between Warthin tumors and malignant lesions. This study evaluated the diagnostic value of quantitative permeability MRI based on dynamic contrast-enhanced pharmacokinetic analysis for differentiating salivary gland tumors. Methods: This retrospective single-center study included 51 patients with 59 histologically confirmed salivary gland lesions examined between January 2022 and November 2024. MRI included diffusion-weighted imaging and dynamic contrast-enhanced MRI (DCE-MRI). Quantitative pharmacokinetic analysis based on the Extended Tofts model provided Ktrans, Kep, Ve, and Vp. Interobserver reproducibility was assessed using the intraclass correlation coefficient, and diagnostic performance was evaluated by receiver operating characteristic analysis. Results: Of 59 lesions, 44 were benign, and 15 were malignant. Warthin tumors showed significantly higher Kep values than malignant lesions (median, 998 vs. 480 × 10^-3/min; p = 0.002) and lower Ve values (median, 121 vs. 245 × 10^-3; p = 0.004). ADC values partially overlapped between Warthin tumors and malignant lesions. Interobserver agreement was good, with ICC values ranging from 0.78 to 0.86. Kep showed the highest diagnostic performance in this cohort, with an AUC of 0.96. A Kep threshold of 723 × 10^-3/min yielded 92.3% sensitivity and 93.3% specificity. Conclusions: Quantitative DCE-MRI, particularly Kep, may provide additional information for differentiating Warthin tumors from malignant salivary gland lesions within a multiparametric MRI assessment. The threshold identified in this cohort is exploratory and requires external validation before routine clinical use.