[Value of DCE-MRI and DWI in the differential diagnosis of inflammatory pseudotumor and lymphoma in the lacrimal gland].

Objective: To evaluate the value of dynamic contrast-enhanced MR (DCE-MRI) and diffusion weighted MR (DWI) in differential diagnosis of inflammatory pseudotumor and lymphoma in the lacrimal gland. Methods: In this retrospective study, a total of 24 cases of inflammatory pseudotumor and 22 cases of lymphoma in the lacrimal gland at Beijing Tongren Hospital confirmed by histological results were enrolled from January 2010 to January 2015.DCE-MRI and DWI were performed in these cases, and the type of time-signal intensity curve (time-intensity curve, TIC), the peak contrast index (CIpeak), maximum enhancement ratio (ERmax), washout ratio (WR) and ADC value were analyzed.Differences of these parameters between inflammatory pseudotumor and lymphoma in the lacrimal gland was evaluated by independent samples t test or Mann-Whitney U test.The receiver operating characteristic analysis was used to evaluate the utility of these parameters in discriminating the two diseases. Results: Type of TIC, CIpeak, WR, ERmax and ADC values were statistically different (all P<0.05) between the inflammatory pseudotumor and lymphoma in the lacrimal gland.ERmax, CIpeak and ADC values of inflammatory pseudotumor were greater than those of lymphoma, but the WR values of inflammatory pseudotumor was less than those of lymphoma.The area under the ROC of the CIpeak, WR, ERmax and ADC values was 0.68±0.08, 0.70±0.08, 0.70±0.08, 0.84±0.81 respectively.Using an ADC(b=0, 1000) value of 1.005×10(-3) mm(2)/s as the diagnostic threshold, the sensitivity, specificity and accuracy to differentiate benign lesions from malignant lesions were 84.2%, 65.0% and 75.0% respectively.The diagnostic ability of DWI combined with DCE-MRI was superior to that of DCE-MRI(P=0.000) or DWI alone(P=0.008) with overall sensitivity, specificity and accuracy of 86.3%, 87.5% and 86.9%. Conclusion: DCE-MRI and DWI may improve the diagnostic accuracy in differentiation of the inflammatory pseudotumors and lymphomas in the lacrimal gland, and play an important role in differentiation among them.