Objective To evaluate the clinical impact of whole body diffusion weighted imaging （WB-DWI） on diagnosis and staging of malignant lymphoma. Methods Thirty-one patients with suspected lymphadenopathy were enrolled. WB-DWI was performed by using short TI inversion recovery echo-planar imaging sequence with free breathing and built-in body coil. Axial T2- weighted imaging images of the same location were used as reference. The results of WB-DWI were compared with pathological results and other imaging modalities. The mean apparent diffusion coefficient （ADC） values of different kinds of lymph nodes were compared. Results WB-DWI was positive in all 18 cases with lymphoma

5 cases with metastatic lymph nodes and 4 of 8 cases with benign lymphadenopathy. The mean ADC value of lymphomatous

metastatic and benign lymph nodes was （0.87 ± 0.17） × 10-3

（0.98 ± 0.09） × 10-3 and （1.20 ± 0.10） × 10-3 mm2/s. There was significant difference in ADC value between benign lymph nodes and other two groups （P < 0.01）. The sensitivity

specificity and accuracy of WB-DWI in diagnosis of lymphoma were 100% （18/18）

30.8% （4/13） and 71.0% （22/31）. When an ADC value of 1.08 × 10-3 mm2/s was used as the threshold value for differentiating malignant from benign lymph nodes

the best results were obtained with sensitivity of 87.8% and specificity of 91.3%. Sixteen of eighteen cases （88.9%） of lymphoma were accurately staged in accordance with clinical staging. Conclusions WB-DWI is a sensitive

but less specific technique for diagnosis of lymphoma. It is difficult to differentiate lymphomatous from metastatic lymph nodes using WB-DWI. However

it is a valuable imaging modality for staging of patients with malignant lymphoma.