Abstract:      Background and purpose: Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) can be used for magnetic resonance imaging systemic examination, especially in examing the metastatic lesions, lymph node and bone diseases, and the imaging result is similar with PET. This study aimed to evaluate the application value of magnetic resonance DWIBS and positron emission tomography with computed tomography (PET/CT) on malignant metastatic diseases. Methods: Thirty-six patients confirmed with malignant tumors accompanying metastasis by the pathology of operation or biopsy underwent both DWIBS imaging and PET/ CT, chi-square test and Kappa test were used for comparing the detection results of metastasis by these 2 imaging methods. Results: Among the 36 malignant tumor patients with 238 metastatic lesions, 218 (91.6%, 218/238) lesions in DWIBS and 209 (87.8%, 209/238) lesions in PET/CT were detected, with 200 lesions detected by the two methods simultaneously, and the concordance rate was 88.7% (211/238); but there was no statistical significance between this two methods (χ²=1.843, P=0.157). Kappa test showed a fair concordance rate between DWIBS and PET/CT (P=0.000). There were different significance between DWIBS and PET/CT in detecting metastatic lesions of brain and bone (P=0.005 and 0.031); But there was no significant differences (P=0.309 and 1.000) in detecting metastatic lesions of lymph nodes and liver. Conclusion: DWIBS could detect metastatic lesions effectively, and there is fine consistency with PET/CT. DWIBS is more sensitive than PET/CT in detecting metastatic lesions of brain and bone, so DWIBS
could be chosed for screening metastatic lesions according to the characteristics of different primary tumors.

Key words: Diffusion-weighted whole-body imaging with background body signal suppression, Magnetic resonance imaging, Tumor, Metastasis, Positron emission tomography with computed tomography