Dichotomous Indium-111 labeled leukocyte scan findings while evaluating osteomyelitis in a failed mandibular graft

Markedly elevated111 In labeled leukocyte activity suggestive of acute osteomyelitis was observed in a region of a composite mandibular allograft that was photon deficient on 99mTc MDP bone scintigraphy. This finding was later confirmed by surgical pathology. The patient was treated with intravenous antibiotics and returned two months later with persistent bone infection. The foHow-up three phase bone and 111In labeled leukocyte scans were performed. The photopenic region noted in the previous bone scan demonstrated a mild interval increase in activity, while the 111In labeled leukocyte activity was essentially normal. Additional imaging of the composite allograft was then performed using 67Ga-citrate at 24 and 48 hours post injection. These images revealed focal areas of increased Gallium activity in the photopenic region of the graft exhibiting normal mIn leukocyte activity. The tissue culture comfirmed underlying chronic osteomyelitis. We conclude that normal uptake on niIn labeled leukocyte and photon deficient regions on 99mTc bone scintigraphy do not necessarily exclude the presence of chronic osteomyelitis. In the management of patients who have been on prolonged antibiotic therapy with persistent infection, 67Ga scintigraphy is warranted.