Developing an MRI protocol at 1.5 T allowing quantification of the hematopoietic, fatty and trabecular moieties of marrow. An ideal protocol would differentiate red marrow from neoplastic cellular infiltration, and detect loss of trabecular bone. This study assesses the feasibility of a multiple gradient echo sequence for differentiation of water and fat constituents of marrow, combined with T2* mapping to interrogate the trabecular component The investigators hypothesize that these techniques will allow better identification of lesion type than routine MR sequences, and can be used to quantitatively characterize myelomatous marrow replacement, with iliac crest biopsy (which is routinely performed in the diagnosis of myeloma) as gold standard.