Abstract： OBJECTIVE To investigate the value of magnetic resonance imaging(MRI)parameters in differentiation between olfactory neuroblastoma(ONB)and sinonasal diffusion large B cell lymphoma(DLBCL).METHODS Pathology-proven 34 ONB patients and 29 DLBCL patients with MRI examinations before treatment were included.The conventional MRI features and semi-quantitative parameters of two groups were documented and analysis.Statistical analysis between the two groups were performed.The independent sample t-test and was used for continuous variables in normal distribution,Mann-Whitney U test was used for non-normal distribution.The frequency of categorical variables were compared by Chi-square test.Logistic regression analysis was done to identify the most predictive MRI features for differentiation.RESULTS ONB often located in the nasal cavity olfactory recess and ethmoid sinus,characterized by intracranial extension through the cribriform plate,forming a'dumbbell'shape mass(P=0.004).DLBCL more often located in paranasal sinus,orbits(P<0.001,P=0.024).T2WI signal intensity of ONB were higher than DLBCL(P<0.001).ONB showed more signs of outward turbinate and lobulation(P=0.001,P=0.004).ADCave of ONB was obviously higher than DLBCL(P<0.001).On DCE-MRI,ONB showed higher CImax,WR(P<0.001,P=0.011),lower TTP than DLBCL(P=0.003).ONB presented more wash-out type TIC curve(P=0.022).Logistic regression analysis demonstrated that tumor location(olfactory cleft or maxillary sinus),T2WI intensity,ADCave with cutoff value of 0.82×10-3mm2/s and TTP with cut off value of 52 seconds were the most predictive MRI features for differentiation.CONCLUSION The multiple MRI conventional and functional parameters are helpful in differentiating ONB from DLBCL.