Polyclonal, nonspecific ¹¹¹In-IgG scintigraphy in the evaluation of complicated osteomyelitis and septic arthritis

Background. In this investigation we tested the hypothesis that ¹¹¹In-IgG scintigraphy can differentiate infectious from sterile inflammatory processes in patients with complicated osteomyelitis or septic arthritis. Methods. A prospective university hospital based study was performed over 18 months. We studied 31 sites of suspected infection, in 25 adult patients, (age 18 to 74 years, 12 females and 13 males) referred with clinical presentations compatible with complicated osteomyelitis or septic arthritis and in whom proof of the infection was likely to be obtained. The clinical setting in these patients was previous trauma, recent surgery, peripheral vascular disease or adjacent soft tissue infection. Whole body scintigraphy was performed at 1-6, 18-24 and 42-48 hours after administration of 55 MBq of ¹¹¹In-IgG and results were compared to radiographs, (99m)Tc- MDP skeletal scintigraphy, biopsy specimens (9 sites) or synovial fluid aspirates (4 sites) and clinical follow-up. Results. Of the 31 sites evaluated, 68% (21/31) were interpreted as negative for abnormal tracer accumulation and 32% (10/31) were considered positive. In patients who underwent biopsy and/or synovial fluid aspiration, 6 of 7 sites were correctly interpreted as positive; sensitivity 86%. Five of 6 sites were correctly interpreted as negative; specificity 83%. When all patients were considered using clinical follow-up in addition to culture results, 9 of 10 sites were correctly interpreted as positive (sensitivity 90%) and 20 of 21 patients were correctly interpreted as negative (specificity 95%). Conclusions. ¹¹¹In-IgG scintigraphy is useful for detection of musculoskeletal infection in patients in whom sterile inflammatory events simulate infectious processes.