Purpose: To characterize parotid tumors with dynamic susceptibility contrast perfusion-weighted magnetic resonance (MR) imaging and diffusion-weighted MR imaging.
Material and methods: Prospective study was conducted upon 48 consecutive patients (27 men, 21 women; aged 15-75 years; mean, 45 years) with parotid tumors that underwent dynamic susceptibility contrast perfusion-weighted MR imaging was performed after bolus injection of gadopentate dimeglumine and diffusion-weighted MR imaging. The dynamic susceptibility contrast percentage (DSC%) and apparent diffusion coefficient (ADC) values of parotid tumors were calculated and correlated with histopathological findings.
Results: The DSC% of malignant parotid tumors (33.53% ± 3.99%) was significantly different (P = 0.001) from that of benign parotid tumors (22.29% ± 4.13%). The threshold values of DSC% and ADC used in differentiating malignant from benign parotid tumors were 26.5% and 1.07 × 10 mm/s, respectively, with area under the curve (AUC) of 0.96 and 0.81, respectively. The DSC% of malignant parotid tumors was significantly different from that of Warthin tumors (P = 0.001). The cutoff DSC% used to differentiate malignancy from Warthin tumors was 26.9% with an AUC of 0.99. There was a significant difference in DSC% and ADC values between pleomorphic adenomas and Warthin tumors (P = 0.001). The threshold values of DSC% and ADC used in differentiating pleomorphic adenomas from Warthin tumors was 22.5% and 0.99 × 10 mm/s, respectively, with AUC of 0.88 and 0.98, respectively.
Conclusions: Dynamic susceptibility contrast-enhanced perfusion-weighted MR imaging and diffusion-weighted MR imaging are noninvasive promising methods that are used for differentiation of malignant from benign parotid tumors and for characterization of some benign parotid tumors.