RAPID IMAGING OF INFECTIONS WITH A MONOCLONAL-ANTIBODY FRAGMENT (LEUKOSCAN)

The diagnostic accuracy for imaging infection with a technetium-99m-la beled antigranulocyte Fab' fragment (LeukoScan) was prospectively exam ined in a multicenter study. Scintigraphy was performed in 53 patients at 1 to 6 hours and at 24 hours after injection of the labeled antibo dy fragment. Thirty-nine sites of infection were detected and confirme d by histologic study, cytologic study, other imaging procedures,or by followup. Thirty-eight of the 53 patients also were studied with tech netium-99m-Exametazim or indium-111-oxine labeled leukocytes within 1 week of the LeukoScan study. In 21 patients with 25 osteomyelitic lesi ons, LeukoScan recognized 13 of the lesions as being true positive one s, 10 as being true negative ones, and 2 as being false negative ones, whereas the leukocyte scan showed 9 true positive results, 5 true neg ative results, and 2 false negative ones. Sensitivity, specificity, an d diagnostic accuracy of LeukoScan were 90.0%, 84.6%, and 87.9%; and w ith autologous leukocyte scintigraphy were 83.9%, 76.5%, and 81.3%, re spectively. The sensitivity of LeukoScan was independent of the amount of the labeled antibody injected (0.1 - < 0.5 mg, 96.2%; 0.5 - < 0.9 mg, 80.0%; 0.9 - 1.0 mg, 77.8%). False positive lesions were detected in a periprosthetic calcification, a frontal hyperostosis, and 2 perip rosthetic hips that had loosened. Human antimouse antibody could not b e detected in any of the 13 patients tested 1 or 3 months after inject ion. LeukoScan is suitable for imaging infectious lesions and may have diagnostic advantages compared with autologous scintigraphy.