Objective To evaluate the value of MR DWI combined with dynamic contras-t enhanced (DCE)scanning in the differential diagnosis of orbital lymphoma and inflammatory pseudotumor.Methods The clinical and imaging data of 1 5 cases with orbital lymphoma and 10 cases with inflammatory pseudotumor confirmed by surgery and pathology were analyzed retrospectively.25 patients were performed with conventional MR scanning,DWI scanning and DCE scanning.ADW4.7 software was used for DWI images and DCE images pos-t processing for analyzing the two groups of lesions in the TIC subtyping.Independent sample t test statistical analysis was used for comparing two groups of ADC values and Tmax values.The ROC curve was used for determining the statistically significant differences in measurement data of the threshold.With pathologic and immunohistochemical results as the gold standard,the accuracy,sensitivity and specificity of DWI combined with DCE in the diagnosis of orbital lymphoma and inflammatory pseudotumor were further detected.Results Among the 1 5 patients with orbital lymphoma,8 cases (8/15)occurred in the lacrimal gland area,5 cases (5/1 5)occurred in the outer cone space and 2 cases (2/15)occurred in the eyelid.Among the 10 patients with inflammatory pseudotumor,6 cases (6/10)occurred in the lacrimal gland and 4 cases (4/10)in the bulb.Among the 25 patients,9 of them had the TIC curve of outflow,6 of them had the TIC curve of platform and 10 of them had the TIC curve of inflow.The ADC value of orbital lymphoma was (0.573 ±0.1 1 6)×10－3 mm2/s,and the Tmax value was (248.2±1 59.4)ms.The ADC value of inflammatory pseudotumor was (1.186±0.244)×10－3 mm2/s,and the Tmax value was (5 5 7.6 ±98.7)ms.With the ADC＝0.885×10－3 mm2/s for the threshold,the AUC was 0.9 3 6 ,with diagnostic accuracy of 9 1.3%, the sensitivity of 90.1% and specificity of 80%.With the Tmax＝481.2 ms as the threshold,the AUC was 0.927,with the diagnosis accuracy rate of 88%,the sensitivity of 80%,and the specificity of 86.7%. Finally,DWI combined with DCE could reach the AUC 0.945, diagnostic accuracy of 89.5%,sensitivity of 93.3%,and specificity of 82.6%.Conclusion Conventional MRI scan combining DWI with DCE could show the histological components of the lesion of orbital tumor,which is of certain significance for the qualitative diagnosis of orbital lymphoma and inflammatory pseudotumor.