Current concepts in MRI of focal and diffuse malignancy of bone marrow

Bone marrow is a ubiquitous component of musculoskeletal imaging studies. The ability to identify and characterize pathology accurately in the bone marrow can be challenging given the broad spectrum of imaging features of normal bone marrow. Knowledge regarding the ability to differentiate normal from abnormal marrow has been enhanced with MR imaging with numerous techniques available to aid in distinguishing benign from malignant lesions in the bone marrow. T1-weighted fast spin echo (FSE) and fluid-sensitive sequences, fat-saturated T2-weighted FSE, and short tau inversion recovery provide valuable tools for the evaluation of a focal bone marrow lesion. Gadolinium enhancement, chemical shift, diffusion-weighted, and MR spectroscopy imaging are additional tools available for focal bone marrow lesion evaluation. Whole-body MRI and fluorodeoxyglucose positron emission tomography-computed tomography have evolved to be useful studies for staging and monitoring of therapeutic response in whole-body imaging. The relative advantages and disadvantages of the whole-body techniques are reviewed for metastases, myeloma, and lymphoma.