ObjectivesThe aim was to evaluate the potential use of diffusion-weighted imaging(DWI)and dynamic contrast-enhanced MRI(DCE-MRI)in differentiating benign from malignant lesions in floor of the mouth(FOM).MethodsA retrospective review was conducted of patients with pathologically confirmed non-cystic FOM lesions between January 2010 and December 2014.The apparent diffusion coefficient(ADC)and time-signal intensity curve(TIC)pattern were assessed.Receiver operating characteristic(ROC)and logistic regression analyses were performed to evaluate their differential value and association with malignancy.Results Significant differences were detected between benign and malignant lesions in ADC value and TIC pattern(p = 0.015 and p< 0.001).The areas under the curve(AUCs)for ADC and TIC pattern were 0.754 and 0.704,respectively.The joint association of ADC and TIC with malignancy was most prominent in lesions with both ADC≤1.23×10-3mm2/s and plateau/washout TIC pattern.The AUC of combined use of ADC value and TIC pattern was 0.820(best sensitivity: 98.3%; best specificity: 88.9%).Conclusion Our results suggest that DWI and DCE-MRI contribute to differential diagnosis of non-cystic MOF lesions,especially when used in combination.Additional larger studies are warranted to confirm our findings.