RADIONUCLIDE IMAGING IN ORTHOPEDIC INFECTIONS

In otherwise normal bone, Three Phase Bone Scintigraphy is sensitive a nd specific for osteomyelitis. In patients with underlying osseous abn ormalities the specificity of the study is decreased, The four phase b one scan, bone/gallium scintigraphy, leukocyte imaging, leukocyte/bone and leukocyte/marrow studies have all been reported to increase speci ficity. The techniques, strategies, and limitations are discussed, No single study is equally useful in all situations. Labeled leukocyte im aging is of little value in vertebral osteomyelitis because this entit y often presents as a nonspecific photopenic defect. The preferred tec hnique for the spine is bone/gallium imaging. Intense uptake, on bone scintigraphy, in two adjacent vertebrae with loss of the disc space is highly suggestive of spinal osteomyelitis. Gallium not only enhances the specificity of the diagnosis but provides information about surrou nding soft tissue infection. In the diabetic foot, labeled leukocyte i maging alone is sufficient to determine the presence of osteomyelitis in the forefoot, In the midfoot and hindfoot it may be necessary to co mbine leukocyte scintigraphy with bone scintigraphy to precisely local ize the infection. Labeled leukocytes accumulate in the uninfected neu ropathic joint and preliminary data suggest that leukocyte/marrow imag ing may be useful to determine the significance of such uptake. For th e painful joint replacement, if infection is the primary concern, leuk ocyte/marrow scintigraphy should be performed initially. If any post-o perative complication, regardless of type, is the concern, it is reaso nable to begin with bone scintigraphy because a normal study rules str ongly against any complication. An abnormal bone scan will require add itional studies to more precisely determine the cause of that abnormal ity. Copyright (C) 1997 by W.B. Saunders Company.