White blood cell scintigraphy with monoclonal antibodies in the study of the infected endoprosthesis.

Forty-three patients with suspected infection of a hip or a knee prosthesis were studied with white blood cell scintigraphy (WBC), using technetium-99m (n = 37) or iodine-123 (n = 6) labelled monoclonal mouse antibody (MoAb). Previously, all patients had undergone skeletal scintigraphy, which was performed as a three-phase study in 33 cases. The final diagnosis was established by open surgery, histology and culture in 37 cases, by puncture and culture in 3 cases, and by clinical follow-up of at least 6 months in 3 cases. Eighteen prostheses were infected, 25 uninfected. The delayed phase of skeletal scintigraphy had a sensitivity of 92%, a specificity of 24% and an accuracy of 48% in the detection of infection. The perfusion and blood pool activity of the three-phase bone scan had a sensitivity of 67%, a specificity of 71% and an accuracy of 70%. The diagnostic value of WBC was sensitivity 89%, specificity 84% and accuracy 86%. WBC with 99m-Tc-MoAb is easy to perform and always available. Its diagnostic accuracy is similar to conventional WBC scintigraphy with either indium-111 or technetium-99m.