Objective: To determine the diagnostic value of combining conventional MRI, diffusion-weighted imaging (DWI) and dynamic contrast enhanced MRI (DCE-MRI) in salivary gland tumors.
Methods: 45 patients with salivary gland tumors were evaluated with conventional MRI, DWI and DCE-MRI prior to surgery and confirmed by pathologic findings. The apparent diffusion coefficient (ADC) was calculated from DWI that was obtained with a factor of 0 and 1000 s mm-2. A time-intensity curve (TIC) was obtained from DCE-MRI.
Results: In conventional MRI, benign tumors often showed well-defined and clear margins, malignant tumors showed irregular margins or infiltration into the surrounding tissue. There were significant differences with regard to the ADC values between pleomorphic adenoma (1.72 ± 0.29 × 10-3 mm2 s-1) and malignant tumors (0.95 ± 0.09 × 10-3 mm2 s-1, p < 0.05) and between adenolymphoma (0.74 ± 0.05 × 10-3 mm2 s-1) and malignant tumors (p < 0.05). However, there was no significant differences in term of the ADC values between benign tumors (1.33 ± 0.52×10-3 mm2 s-1) and malignant tumors. DCE-MRI showed benign tumors with A-type, B-type and D-type of TICs, and the malignant tumors with C-type TICs. A combination of all of these parameters yielded sensitivity, specificity, accuracy, and positive and negative predictive values of 90%, 97%, 95%, 90 and 97%, respectively.
Conclusion: An evaluation combining MRI morphologic findings and functional MRI (ADCs and TIC) appears to be useful in differentiating benign from malignant tumors in salivary gland tumors. Advances in knowledge: The study firstly dealt with the combination of conventional MRI, DWI-MRI with DCE-MRI in salivary gland tumors.