Skeletal imaging and management of bone disease.

Up to 90% of patients with multiple myeloma develop bone lesions. The lesions are purely osteolytic because of increased osteoclast activity and markedly suppressed or absent osteoblast activity. The "gold standard" for imaging myeloma bone lesions is the metastatic bone survey. However, plain radiographs are relatively insensitive and can only demonstrate lytic disease when 30% of trabecular bone loss has occurred. Technicium-99m bone scanning is not appropriate for evaluating myeloma patients since bone scans underestimate the extent of bone involvement in patients with myeloma. The limited reproducibility of bone surveys have led to the use of computerized tomography (CT) scanning, magnetic resonance imaging (MRI) and positron emission tomography (PET) scans to evaluate the extent of bone disease. CT scans are more sensitive than plain radiographs for detecting small lytic lesions, and MRI scans detect marrow involvement by the tumor. PET scans have been used to detect bone lesions in patients with myeloma, are more sensitive than plain radiographs, and have the same sensitivity as MRIs for detecting bone disease in the spine and pelvis. Treatment of myeloma bone disease involves treatment of the underlying malignancy and its manifestations. Current treatments that will be discussed include bisphosphonate therapy, kyphoplasty, vertebroplasty, radiation therapy, and novel agents to suppress osteoclastic bone resorption. In addition, complications with bisphosphonate therapy will be reviewed, in particular, osteonecrosis of the jaw associated with bisphosphonate therapy. As survival of myeloma patients increases, therapies to prevent the complications of aggressive myeloma bone disease become more important.