Bone scintigraphy is quite sensitive to bone pathology, but not very specific as it can be positive with fracture, primary and metastatic neoplasms, heterotopic ossification, arthritis, osteomyelitis, and osteoarthropathy.
Gallium-67 imaging localizes in inflammatory lesions and can add diagnostic specificity. Its intense concentration is thought to indicate osteomyelitis. It may show mildly increased uptake in nonseptic diabetic osteoarthropathy, but has been reported by Glynn to occasionally show marked accumulation adding further confusion to a difficult problem.
Indium-111 labeled white blood cells have been found to be very specific for acute osteomyelitis and have been found to be quite helpful in the differentiation of nonseptic from septic osteoarthropathy in diabetic patients.
Maurer, et al performed a retrospective study of thirteen diabetic patients in whom Indium-111 leukocyte studies were performed for possible osteomyelitis. The patients also had radiographic evidence of osteoarthropathy. Three-phase scintigraphy was performed in all patients and showed increased uptake in both septic and nonseptic osteoarthropathy with a sensitivity of 75% and a specificity of 56% for osteomyelitis. Leukocyte imaging had the same sensitivity but was most helpful for excluding infection with a specificity of 89%.
Schauwecker, et al studied the use of bone imaging, leukocyte imaging, and gallium imaging in the setting of suspected osteomyelitis superimposed upon other diseases causing increased bone turnover. In-111 leukocyte imaging had a sensitivity of 100% in acute osteomyelitis and 60% in chronic osteomyelitis with a specificity of 95%. Gallium-67 was excellent for ruling out osteomyelitis when it was a normal study or ruling it in when it showed hyperintense uptake compared with bone imaging or had a different distribution from the bone images. This situation occurred in 28% of the patients studied.
Splittgerber, et al. studied six diabetic patients with radiographic findings of osteomyelitis, osteoarthropathy or both using leukocyte and bone imaging. Three patients actually had osteomyelitis. Bone images showed increased uptake in all six patients studied while leukocyte imaging showed increased uptake only in the three patients with osteomyelitis.
In conclusion, Indium-111 labeled leukocyte imaging may add further specificity in differentiating septic from nonseptic diabetic osteoarthropathy in patients with increased uptake shown on bone and/or gallium images.
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3) Splittgerber GF, et al. Combined leukocyte and bone imaging used to evaluate diabetic osteoarthropathy and osteomyelitis. Clin Nucl Med. 1989; 14(3):156-60.
4) Schauwecker DS, et al. Evaluation of complicating osteomyelitis with Tc-99m MDP, In-111 granulocytes, and Ga-67 citrates. J Nucl Med. 1984; 25:849-53.
5) Maurer AH, et al. Infection in diabetic osteoarthropathy: Use of indium-labeled leukocytes for diagnosis. Radiology 161:221-225.
J. Anthony Parker, MD PhD, email@example.com