GIÁ TRỊ CỘNG HƯỞNG TỪ KHUẾCH TÁN TRONG CHẨN ĐOÁN U TUYẾN NƯỚC BỌT MANG TAI LÀNH TÍNH VÀ ÁC TÍNH THƯỜNG GẶP

Abstract

Objectives: To characterize the magnetic resonance imaging (MRI) features of common benign and malignant parotid gland tumors (PGTs) and to evaluate the diagnostic value of MRI—particularly diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC)—for differentiating benign from malignant lesions. Methods: We conducted a cross-sectional descriptive study of 39 patients with PGTs who underwent MRI at Ho Chi Minh City Oncology Hospital, Viet Nam, between January 2019 and June 2025, with histopathology as the reference standard. Conventional MRI morphology and DWI were assessed. Quantitative measurements included lesion ADC (ROI placed on the solid components), ADC of normal parotid parenchyma, and the ratio rADC (lesion-to-parotid ADC). Results: Compared with benign PGTs, malignant tumors more frequently exhibited ill-defined margins, absence of a capsule, peritumoral edema (60.9%), invasion of adjacent tissues (47.8%), and cervical lymphadenopathy (30.4%) (all p<0.05). On DWI, 56.5% of malignant PGTs showed marked diffusion restriction (high DWI signal with low ADC), whereas most benign tumors did not. Mean lesion ADC measured in the solid components was significantly lower in malignant than in benign tumors (p<0.001). Receiver operating characteristic (ROC) analysis with the maximal Youden index identified an optimal ADC cutoff of 1.06 × 10⁻³ mm²/s, yielding 78.3% sensitivity and 93.7% specificity for malignancy. The rADC was also significantly lower in malignant tumors (1.04) than in benign ones (1.32; p=0.001). Conclusion: MRI reliably differentiates benign from malignant parotid gland tumors. A combined approach—systematic assessment of morphological features together with quantitative ADC measured in the solid tumor components—provides strong diagnostic discrimination.