Imaging changes and pain relief were compared in 21 patients with intra- versus extra-osseous bone metastases treated palliatively with magnetic resonance guided high intensity focused ultrasound (MRgHIFU). Thermal dose volumes measured on proton resonance frequency shift (PRFS) thermometry were significantly larger in the extra-osseous group. Intra-osseous lesions showed focal non-enhancement by Day 30, and patients had better pain response to MRgHIFU than those with extra-osseous lesions. By Day 30, 67% (6/9) patients with intra-osseous lesions were responders, compared with 33% (4/12) of patients with extra-osseous lesions. In neither group was pain response indicated by non-enhancement on Gd-T1W imaging.