Symptomatic and Scintigraphic Improvement after Intravenous Pamidronate Treatment of Paget’s Disease of Bone in Patients with Normal Serum Alkaline Phosphatase Levels

Imaging Findings and Evaluation of Metabolic Bone Disease

Bone is a dynamic organ of the endoskeleton, playing an important role in structural integrity, mineral reservoirs, blood production, coagulation, and immunity. Metabolic bone disease encompasses a broad spectrum of inherited and acquired disorders that disrupt the normal homeostasis of bone formation and resorption. For patients affected by these processes, radiologic imaging plays a central role in diagnosis, monitoring treatment, and risk stratification. Radiologists should be familiar with the diseases, intimately aware of the imaging findings, and possessive of multimodality expertise to wisely guide the best practice of medicine. The purpose of this paper is to review the imaging features and characteristics of the most common types of metabolic bone disease with highlights of clinically relevant information so that readers can better generate appropriate differential diagnoses and recommendations. For this review, a thorough literature search for the most up-to-date information was performed on several key types of metabolic bone disease: osteoporosis, osteomalacia, rickets, scurvy, renal osteodystrophy, hyperparathyroidism, Paget’s disease, osteogenesis imperfecta, acromegaly, and osteopetrosis. Although they all affect the bone, these diseases have both shared characteristic features that can be discerned through imaging.

Synchronous Paget disease of bone and hyperparathyroidism: report of a case with extensive craniofacial involvement

Paget disease of bone (PDB) and hyperparathyroidism (HPT) are metabolic osseous disorders which affect ≥2% of the population. As these diseases may share clinical, radiographic, biochemical, and histopathologic features, knowledge of their phenotypic overlap may provide diagnostic utility and improve clinical outcome. Scant information is available in the dental literature regarding patients concurrently affected with both pathologies. We present an unusual case report of a 63-year-old woman coaffected with primary HPT, attributed to a functional oxyphilic parathyroid adenoma, and PDB. Bone scintigraphy revealed pagetoid lesions of the skull, humeral head, spine, sacrum, and hemipelvis. Salient craniofacial features noted were bony involvement of the calvarium and midface, resulting in extensive maxillary overgrowth, hearing loss, telecanthus and consequent visual impairment, nasal deformity, and leontiasis ossea. The patient underwent a partial parathyroidectomy and bisphosphonate administration was to be initiated upon extraction of the remaining dentition.

Imaging of metabolic bone diseases

Bone scintigraphy and X-ray are complementary in the assessment of Paget's disease. Whereas bone scintigraphy allows visualization of the whole skeleton and 'hot spots', X-ray enables visualization of more detailed images of the pagetic bone lesion. X-ray may be invaluable in the diagnosis of osteomalacia, especially in children. As osteomalacia is characterized by impaired bone mineralization, the use of bone density measures may lead to misinterpretation of the condition as osteoporosis. Dual-energy X-ray absorptiometry at the femoral neck is the 'gold standard' for the assessment of osteoporosis. However, all devices are useful to predict the risk of fracture. In the future, high-resolution computer tomography and magnetic resonance imaging may become valuable clinical tools, capturing the architectural aspect of bone strength and improving fracture prediction models.

Scintigraphic, biochemical, and clinical response to zoledronic acid treatment in patients with Paget's disease of bone

Bisphosphonates have long been used with success in the treatment of Paget's disease of bone (PDB). The aim of this study was to evaluate the early (up to 3 months) and late (at 12 months) scintigraphic, biochemical, and clinical response to a single intravenous infusion of zoledronic acid (ZOL) in patients with PDB serially assessed for 1 year. Nine patients with 30 bone lesions caused by PDB were prospectively evaluated. Total serum alkaline phosphatase (SAP) was serially measured. Scintigraphy was performed before and at 3 and 12 months after ZOL administration, and bone lesions were assessed quantitatively. After treatment, pain was alleviated in five of six patients starting from the first month. At 3 months, a significant decrease of SAP levels compared to baseline values was found (322 +/- 211 IU/l before vs. 101 +/- 36 IU/l 3 months after; P < 0.05), with normal values attained in all except one patient. The scintigraphic index of involvement (SII), a marker for the per-patient activity of the disease, was reduced from 14.4 +/- 7.6 to 7.2 +/- 1.8 (P = 0.01). The scintigraphic ratio (SR), a marker for the per-lesion activity of the disease, was reduced from 12.8 +/- 7.7 to 7.0 +/- 2.9 (P < 0.001). The values of markers of disease activity remained unchanged up to 12 months. A single intravenous administration of ZOL leads to a favorable clinical, biochemical, and scintigraphic response in patients with PDB starting as early as 3 months after treatment and lasting no less than 12 months (i.e., considerably longer than the other existing therapies).