It is important to review the physics of current MRI developments in nontraumatic spinal imaging and their specific applications for assessing the bone marrow. Techniques include chemical shift imaging and its use in differentiating aggressive from benign lesions and in confirming the presence of diffuse red marrow conversion, which may mimic diffuse marrow infiltration in metastatic disease. The principles of dynamic contrast MRI and its uses in multiple myeloma and discriminating between postoperative change/scarring versus recurrence in soft-tissue tumors warrant discussion. The basic physics of diffusion-weighted imaging (DWI) in bone marrow pathologies are distinguished from the principles of DWI as applied to solid organs, and DWI is used in the staging of multiple myeloma and in differentiating between benign versus malignant compressive vertebral fractures. The orthopaedic surgeon should be knowledgeable about whole-body MRI principles and its uses in staging multiple myeloma and sarcoma. Knowledge about PET-MRI principles and its limitations as well as its potential use in assessing the subchondral bone plate and bony remodeling is also important. This technique may play a role in the future for predicting progression to osteoarthritis.