Osteomyelitis: diagnosis with (99m)Tc-labeled antigranulocyte antibodies compared with diagnosis with (111)In-labeled leukocytes--initial experience.

Abstract

To compare a technetium 99m-labeled murine immunoglobulin M monoclonal antigranulocyte antibody that binds to human polymorphonuclear leukocyte CD15 antigens with indium 111 ((111)In)-labeled leukocytes in the diagnosis of appendicular skeletal osteomyelitis. Twenty-four patients suspected of having infected joint replacement (n = 12), diabetic pedal osteomyelitis (n = 8), or long bone osteomyelitis (n = 4) were imaged 5, 30, 60, and 120 minutes after antibody injection. Following injection, one patient experienced moderate joint pain exacerbation that resolved spontaneously. Patients underwent imaging with (111)In-labeled leukocytes and three-phase bone imaging. All studies were interpreted alone. Images obtained in antibody and (111)In-labeled leukocyte studies were also interpreted with the bone scans. One reader, without knowledge of other study results or final diagnoses, reviewed and interpreted images in a random order. Sensitivity, specificity, and accuracy were calculated for the antibody study at each time point, the (111)In-labeled leukocyte study, the three-phase bone scanning procedure, and dual-tracer studies. There were 11 cases of osteomyelitis. Bone scintigraphy was sensitive (1.0) but nonspecific (0.38). Images obtained in the 120-minute antibody study were sensitive (0.91), moderately specific (0.69), and comparable to those obtained in the (111)In-labeled leukocyte study (0.91 sensitivity, 0.62 specificity). When interpreted with bone scans, images obtained in the antibody and (111)In-labeled leukocyte studies showed improved sensitivity and specificity (1.0 and 0.85 and 1.0 and 0.77, respectively). Use of the monoclonal antigranulocyte antibody was comparable to the use of (111)In-labeled leukocytes in the diagnosis of appendicular skeletal osteomyelitis. The combined results of the monoclonal antibody study and bone scanning were more accurate (0.91) for diagnosing this entity than were the results of any of the other studies.