Objective To evaluate the value of whole-body diffusion weighted imaging(WB-DWI) on detection of malignant metastasis.Methods Forty-six patients with malignant tumors underwent WB-DWI examinations between April 2007 and August 2007 in our hospital.Before WB-DWI examination,the primary cancers of all the patients were confirmed by pathology,and the TNM-stage was assessed with conventional magnetic resonance imaging(MRI) or computed tomography(CT).WB-DWI was performed using short TI inversion recovery echo-planar imaging(STIR-EPI) sequence.Abnormal high signal intensities on WB-DWI were considered as metastases.The results of WB-DWI were compared with other imaging modalities.For the assessment of the diagnostic capability of WB-DWI,WB-DWI were compared with CT for demonstrating mediastinal lymph node metastases and lung metastases,and with conventional MRI for demonstrating metastases in other locations.Results WB-DWI demonstrated 143 focuses,14 of which were diagnosed to be benign lesions in routine imaging.The number of bone metastases depicted on WB-DWI and routine imaging was 85 and 86;lymph node metastases was 17 and 18;liver metastases was 14 and 14;lung metastases was 4 and 8;and brain metastases was 6 and 8,respectively.WB-DWI failed to detect 12 metastatic lesions including 3 osteoplastic bone metastases,4 lung metastases,3 mediastinal lymph node metastases,and 2 brain metastases.Four metastatic lesions including 2 deltopectoral lymph nodes and 2 rib metastases were detected with WB-DWI alone,all of which evolved greatly during clinical follow-up for more than 6 months.WB-DWI had higher detection rates for metastatic lesions in liver,bone,and lymph nodes than those in lung and brain(χ2=30,P<0.001).Conclusions WB-DWI could detect most of metastatic lesions that were diagnosed with conventional MRI and CT.The limitations of WB-DWI might be had high false-positive rate and low efficiency in detecting mediastinal lymph node,brain,and lung metastases. Objective To evaluate the value of whole-body diffusion weighted imaging (WB-DWI) on detection of malignant metastasis. Methods Forty-six patients with malignant tumors underwent WB-DWI examinations between April 2007 and August 2007 in our hospital. WB-DWI examination, the primary cancers of all the patients were confirmed by pathology, and the TNM-stage was assessed with conventional magnetic resonance imaging (MRI) or computed tomography (CT). WB-DWI was performed using short TI inversion recovery echo- (STIR-EPI) sequence. Abnormal high signal intensities on WB-DWI were considered as metastases. The results of WB-DWI were compared with other imaging modalities. For the assessment of the diagnostic capability of WB-DWI, WB-DWI were compared with CT for demonstrating mediastinal lymph node metastases and lung metastases, and with conventional MRI for demonstrating metastases in other locations. Results WB-DWI demonstrated 143 focuses, 14 of which were diagnosed to be benign lesi ons in routine imaging. The number of bone metastases was on WB-DWI and routine imaging was 85 and 86; lymph node metastases was 17 and 18; liver metastases was 14 and 14; lung metastases was 4 and 8; and brain metastases was 6 and 8, respectively. WB-DWI failed to detect 12 metastatic lesions including 3 osteoplastic bone metastases, 4 lung metastases, 3 mediastinal lymph node metastases, and 2 brain metastases. Four metastatic lesions including 2 deltopectoral lymph nodes and 2 rib metastases were detected with WB-DWI alone, all of which evolved greatly during clinical follow-up for more than 6 months. WB-DWI had higher detection rates for metastatic lesions in liver, bone, and lymph nodes than those in lung and brain (χ2 = 30, P <0.001) .Conclusions WB-DWI could detect most of metastatic lesions that were diagnosed with conventional MRI and CT.The limitations of WB-DWI might be had high false-positive rate and low efficiency in detecting mediastinal lymph node, brain, and lung metastases.