Objectives: The objective of this study was to compare the relative conspicuity of bone metastases on short-tau inversion recovery (STIR) and diffusion-weighted MRI (DWI) whole-body MR sequences for breast, prostate and myeloma malignancies. Methods: 44 whole-body MRI scans were reviewed retrospectively (coronal T 1 weighted, STIR and DWI with b5800). On each scan, up to four of the largest bone lesions were identified on T 1 weighting, and the region of interest signal intensity was measured on STIR and DWI, as well as the background signal intensity. The mean lesion signal to background ratio was calculated for each patient and then for each malignancy group. Results: In prostate cancer patients, the DWI signal/background ratio was greater than that of STIR in 22 out of 24 patients (mean DWI lesion/background ratio 3.91, mean STIR lesion/background ratio 2.31; p50.0001). In multiple myeloma, the DWI ratio was higher in 6/7 patients (DWI group mean ratio 7.59, STIR group mean ratio 3.7; p50.0366). In 13 breast cancer patients, mean STIR and DWI signal/background were similar (DWI group mean ratio 4.13, group mean STIR ratio 4.26; p50.8587). Conclusion: Bone lesion conspicuity measured by lesion/background signal intensity was higher on DWI b5800 than on STIR in patients with prostate cancer and multiple myeloma. DWI should be used in whole-body MR oncology protocols in these conditions to maximise lesion detection. Metastatic disease to bones can be the only site of distant spread in patients with prostate or breast cancer. Accurate detection of such disease dissemination can be challenging as small-volume disease confined to the marrow cavity may be missed on radionuclear bone scintigraphy or CT imaging. Whole-body (WB) MRI is increasingly used in oncological imaging as a tool to improve detection of bone metastases. Several authors report good results compared with other modalites. Baur-Melnyk et al [1] found WB MRI gave superior detection rate and staging for myeloma compared with CT, and Shortt et al [2], evaluating the same malignancy, concluded that WB MRI performed better than positron emission tomography CT. In prostate and breast patients, Gutzeit et al [3] found WB MRI to rank equally with skeletal scintigraphy for detection of bone lesions, and in some cases detected markedly more metastases. In a recent pooled meta-analysis of published studies, WB MRI showed a pooled sensitivity of 90.0% and pooled specificity of 91.8% for the detection of bone metastases [4].WB MRI imaging protocols have evolved with time as MRI scanners are now more technologically advanced. Conventional WB MRI studies have typically employed T 1 weighted (T 1 W) and short-tau inversion recovery (STIR) sequences [1,5,6]. However, more recently, diffusion-weighted sequences are increasingly being utilised [3,7]. The image contrast from diffusion-weighted MRI (DWI) is based on difference in the mobility of water protons between tissues. As the mobility of water protons is impeded more in tumour than in normal tissues, this results ...

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