Magnetic resonance appearance of uncomplicated Paget's disease of bone.

Paget's disease is a disorder of the bone mesenchyma of the skeleton and is a unique condition in which active bone changes can occur without concomitant significant marrow alteration. When present, marrow changes involve predominantly the paratrabecular and endosteal areas, where bone metabolism is increased. At magnetic resonance (MR) imaging, marrow alterations can become prominent and hence confusing in bones with high trabecular content including vertebrae and pelvis. This article addresses the MR appearance of uncomplicated Paget's disease, including normal pagetic bone, predominantly lytic or sclerotic pagetic bone, and unusual partial involvement of the vertebral body. We will emphasize the added diagnostic value of the combination of imaging techniques that depict either osseous changes including radiographs, computed tomography, and bone scintigraphy, or marrow changes, including MR imaging, to contribute to a noninvasive presumptive diagnosis of Paget's disease in atypical presentations.