EVALUATION OF INFECTIONS OF THE LOCOMOTOR SYSTEM WITH INDIUM-111-LABELED HUMAN-IGG SCINTIGRAPHY

Indium-111-labeled human nonspecific immunoglobin G (In-111-IgG) is on e of the newer agents suggested for scintigraphic evaluation of infect ion and inflammation. In this study, the utility of this agent was stu died in routine clinical practice. Methods: A dose of 75 MBq In-111 la beled to 2 mg IgG (MacroScint(R)) was administered intravenously in 22 6 patients with 232 possible foci of infection or inflammation. Imagin g was performed 4, 24 and 48 hr postinjection. The results were verifi ed by culture, obtained either surgically (42%) or via puncture (19%) and long-term clinical and roentgenological follow-up (39%). Follow-up data were used in patients of whom the vast majority had a negative w ork-up, including negative In-111-IgG scintigraphy. Results: All infec ted total hip (THA) and total knee arthroplasties, focal osteomyelitis , diabetic foot infections, septic arthritis and soft-tissue infection s were detected (61 foci). Only one patient with early, low-grade spon dylodiscitis was false negative with In-111-IgG. Since In-111-IgG scin tigraphy does not discriminate between infectious and sterile inflamma tion, careful interpretation is necessary in cementless THA up to 1 yr after insertion, uptake only around the neck of the femoral component of a THA, recent fractures and pseudarthrosis, in which uptake may be caused by sterile inflammation and not by infection (specificity for inflammation 100%, specificity for infection of 77%). Conclusion: Indi um-111-IgG scintigraphy is a very sensitive tool for detection of infe ctious bone and joint disease. Moreover, when uptake patterns of In-11 1-IgG, which are characteristic for sterile inflammation, are excluded , infection can be ruled out with a high degree of certainty.