SIMULTANEOUS ADMINISTRATION OF TC-99(M)-HMPAO-LABELED AUTOLOGOUS LEUKOCYTES AND IN-111-LABELED NONSPECIFIC POLYCLONAL HUMAN-IMMUNOGLOBULIN-G IN BONE AND JOINT INFECTIONS

The aim of this study was to investigate the ability of In-111-labelle d human polyclonal immunoglobulin G (In-111-IgG) to localize bone and joint infections compared with Tc-99(m)-HMAPO-labelled leukocytes (Tc- 99(m)-WBC). Thirty-four patients routinely referred for investigation of bone and joint infections were studied. In all patients, a bone sca n using Tc-99(m)-MDP was initially obtained. Subsequently, Tc-99(m)-WB C and In-111-IgG were simultaneously injected and images obtained at 3 0 min, 4 h and 24 h post-injection. Diagnostic accuracy was establishe d by bacteriology of specimens obtained by needle aspiration and/or su rgery, other imaging methods and clinical follow-up. The images were r ead by three experienced observers blinded to any other information; t he clinical suspicion of infection and the diagnosis were established when two observers agreed. Infection was confirmed in 11 patients. The Tc-99(m)-WBC scans gave 8 true-positive, 5 false-positive, 18 true-ne gative and 3 false-negative results. With In-111-IgG, the figures were 7, 6, 17 and 4, respectively. The sensitivity, specificity and accura cy were 72.7%, 78.2% and 76.4% respectively for the labelled leukocyte s and 63.6%, 73.9% and 70.6% respectively for In-111-IgG. There was gr eater agreement between the observers with Tc-99(m)-WBC than In-111-Ig G. In this study, In-111-IgG was less sensitive and less specific than Tc-99(m)-WBC scintigraphy for the diagnosis of chronic infections, bu t these differences were not significant. Both tracers appear to be us eful in the diagnosis of bone and joint infections. However, our resul ts were less reliable for the diagnosis of an infected prosthesis.