^99mTc-Fab' Fragments (Sulesomab) for Imaging Septically Loosened Total Knee Arthroplasty

Abstract

The diagnostic accuracy of infection scintigraphy with 99m Tc-labelled monoclonal antibody Fab′ fragments (sulesomab) was studied in patients with suspected total knee arthroplasty (TKA) infection. Images from 26 patients were evaluated by two independent readers and compared with a quantitative interpretation of time-activity courses. Microbiological examinations and joint aspiration results were used as reference standards. Histologically, aseptic TKA loosening occurred in two patients and severe, moderate or mild septic loosening in four, nine and 11 patients, respectively. Diagnostic accuracy for severe infection was 100% for both readers, whereas for moderate infection accuracy decreased by 12% and 12% for readers one and two, respectively. For mild infection a further decrease of approximately 61% and 52% occurred for readers one and two, respectively. Quantitative evaluation gave significantly better results over visual interpretation with a diagnostic accuracy of 100% for severe infection and decreased by only 10% and 15% in patients with moderate and mild infection, respectively. Quantitative evaluation of 99m Tc-Fab′ fragments is highly sensitive and specific for diagnostic imaging of infection in patients with septically-loosened TKA.

Prosthetic joint infections: radionuclide state-of-the-art imaging

“…Similarly to in vitro LS, some investigators have also made adaptations to the scanning protocol of AGS, in order to improve the specificity of this modality [64][65][66][67] (Fig. 9).…”

Gliomas with intratumoral abscess formation: Description of new cases, review of the literature, and the role of 99mTC‐Leukoscan

“…The specificity of 99m Tc-Sulesomab in the diagnosis of infectious diseases ranges from 76% to 100% [29]. In addition Gratz et al [7,8] reported an overall sensitivity and specificity of 76% and 84%, respectively, of Leukoscan scintigraphy for the diagnosis of infections involving bone, arthroplastic joint, or other tissues in 138 patients. Similar results were achieved by Cascio et al [30] in patients affected by brucellar spondylitis; the low sensitivity (27.2%) of Leukoscan in these patients was correlated with the chronic phase of the disease.…”

“…A valid option to overcome this limit is the use of antibody fragments instead of intact IgG. Various studies which have adopted 99m Tc-labelled monoclonal antibody fragments ( 99m Tc-Fab 0 fragments, sulesomab) to image infection in specific groups of patients have reported a high degree of sensitivity and specificity [8,28]. The small size of the Fab' fragments (50 kD) means that fast imaging is possible, as early as 1e4 hours post injection, due to rapid uptake into the lesion and a lower degree of background activity, and results in excellent imaging quality.…”

“…Intact murine antibodies represent a valid and simple alternative. They are easy to handle and show rapid results, with high sensitivity and specificity [8]. The major disadvantage in this technique is represented by the development of human antimouse antibodies which can cause serious allergic reactions.…”

“…99m Tc-labeled sulesomab (LeukoScan) (Astrim S.n.C., Milano, Italy), a murine immunoglobulin G subclasses 1 (IgG1) monoclonal antibody fragment antigen binding (Fab') fragment, binds the nonspecific cross-reactive antigen-90, an antigen present on the surface of neutrophils, especially the activated ones [7,8]. Recently, Leukoscan has been shown to play a role as a potential diagnostic tool in infectious of various tissues [7e9].…”