Abstract: Objective To compare MR-diffusion weighted imaging(MR-DWI) with ^99mTc-MDP whole-body bone scan in terms of efficiency and feasibility of MR-DWI in detection of bone metastasis.Methods Twenty patients with malignant tumors and bone metastasis were enrolled.For each patient,bone scan and MR-DWI were performed within one week.The skeletal system was divided into 7 regions:skull,sternum and clavicle,scapula,ribs,spine,pelvis,limbs.Hot spots as well as cold spots in bone scan images with metastatic characteristics and signals higher than background in MR-DWI were distinguished as metastatic foci.Results Except for the spine,MR-DWI displayed fewer metastatic foci than bone scan images in each of the other 6 skeletal regions.Compared with whole-body bone scan,the detection rate of MR-DWI is 59.4%.However,MR-DWI image displayed metastatic foci in 3 cases although their bone scan images were negative.MR-DWI displayed the metastatic foci clearly in one patient with atypical "super scan" by bone scintigraphic image.Conclusion MR-DWI has good detection rate,and can act as the supplement of whole-body bone scan in bone metastasis.Combination of bone scan and MR-DWI will increase the detection rate in bone metastasis detection.

Key words: MR-DWI, ^99mTc-MDP bone scan, bone metastasis