ACR Codes: 4.5
Paget's disease, also referred to as osteitis deformans, is characterized by two phases, an active or osteolytic phase and an inactive/quiescent or sclerotic phase (1,3). The active phase is marked by aggressive bone resorption and subsequent elevation of hydroxyproline, and the inactive phase is marked by decreased bone turnover and elevation of the blood alkaline phosphatase level (1). Increased radiotracer uptake is observed in both phases. Bone involvement is typically polyostotic and most commonly involves the pelvis, followed by the spine, skull, femur, scapula, tibia, and humerus (3). Scintigraphy may show, as alluded to above, osseous expansion as well as other features, to include a characteristic rim of increased uptake bordering a lesion -- referred to as osteoporosis circumscripta -- and an advancing V-shaped tip of increased uptake originating at a subarticular site and extending into the diaphysis of a lone bone -- dubbed the "candle flame" or "blade of grass" appearance. Vertebral findings include a diffusely blastic vertebra, the so-called "ivory vertebra" and a bone-within-bone appearance of an enlarged and square-shaped vertebral body, the "picture frame vertebra" (1) As mentioned above, osseous expansion is best seen on conventional radiographs and CT exams owing to better resolution than that achieved with scintigraphy; however, the bone scan allows visualization of the entire skeleton, thereby making it a superior study in terms of showing extent of disease. Moreover, the bone scan is the more sensitive technique (2).
Reference(s): 1. Dahnert, W. Radiology Review Manual, 2nd ed. Williams and Wilkins: Baltimore; 86-87.
2. Fogelman, I, Carr, D, and Boyle, IT. The role of bone scanning in Paget's disease. Metab Bone Dis Relat Res 1981;3(4-5):243-54.
2. Thrall, JH and Ziessman, HA. Nuclear Medicine: The Requisites, 2nd ed. Mosby: St. Louis; 139-140.
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Disease Topic 4306 
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