Pelvis: Paget’s Disease

Abstract

Paget’s disease (PD) of bone is a metabolic bone disorder involving excessive and abnormal bone remodeling, which alters the architecture and overall appearance of the bone. PD may be monostotic (single bone lesion) or polyostotic (affects multiple bones). It can involve any bone in the body, but has a predilection for axial skeleton. The bone remodeling in the Paget’s disease follows three phases of activity, starting with initial active phase (osteoclastic activity), followed by intermediate mixed phase of abnormal, disorganized, compensatory bone deposition (osteoblastic activity), ending with a quiescent phase (late inactive phase). Radiography is the imaging modality of choice for the diagnosis, whereas bone scintigraphy (BS) helps in staging of the extent of the disease and in treatment response assessment. CT and MRI are useful in the assessment of complications and surgical planning. BS provides whole body skeletal survey, assessing the overall extent of the disease, picking up the lesions missed on other imaging modalities. BS characteristically shows markedly increased uptake in all phases of the disease; however, the late burned out phase may have normal uptake. With the help of the hybrid SPECT/CT, it can work as a “one-stop shop” imaging modality with high sensitivity (of bone scan) and specificity (of CT).