Paget Disease of Bone.

Paget disease (PD) is a common disease of bone associated with abnormal bone turnover that in turn is due to an imbalance between osteoclastic and osteoblastic activity. There is good evidence that PD is reducing in incidence, prevalence, and severity. The disease is most often asymptomatic and is usually detected incidentally on imaging examinations performed for other reasons. The features of PD are relatively specific on radiographs and computed tomography. However, the appearances on magnetic resonance imaging are subtle and nonspecific, although it has become the initial imaging choice for several clinical indications including back pain, neurologic dysfunction, and knee pain. It is therefore important to be familiar with the various imaging appearances of this relatively common disease in an increasingly aging population. In this article we discuss the various imaging appearances of PD and its complications.