This is an open phase II study designed to accumulate preliminary data on the relative diagnostic value of planar bone scintigraphy, whole-body bone SPECT and whole-body bone PET with sodium 18F-Fluoride. We plan to accrue a total of 25 subjects with suspected bone metastases who will undergo planar bone scintigraphy, bone SPECT and a Na18F whole-body bone PET scan.