Value of antigranulocyte scintigraphy with Tc-99m-sulesomab in diagnosing combat-related infections of the musculoskeletal system

AimCombat-related extremity injuries are regularly associated with long-term complications such as chronic infection, especially osteomyelitis. Clinical examination and laboratory parameters do not usually allow reliable diagnosis. In contrast, imaging techniques enable constructive assertions to be made about the location and extent of an infection of the peripheral musculoskeletal system. The aim of this study was therefore to determine the diagnostic reliability of three-phase bone scanning and antigranulocyte scintigraphy using Tc-99m-sulesomab (Leukoscan) in the diagnostic clarification of infections associated with combat-related extremity injuries.MethodsTwenty-seven male patients (mean age 33.9 years) with suspected combat-associated infections of the extremities were included in this retrospective analysis. All patients underwent three-phase bone scanning using Tc-99m-HDP followed by antigranulocyte scintigraphy with Tc-99m-sulesomab. In 26 of the 27 patients, a CT scan of affected limb was obtained, where the secondary fusion with single photon emission CT data set was possible. The diagnostic reliability of imaging techniques was validated against microbiological samples obtained during surgery and used as gold standard.ResultsThree-phase bone scanning yielded a positive result in all patients, with 18 scans classified as true positive (TP) and nine scans as false positive (FP). This produced a sensitivity of 100%, a specificity of 0% and a positive predictive value (PPV) of 67%. Antigranulocyte scintigraphy recognised 13 patients as TP, 1 patient as FP, 8 patients as true negative (TN) and 5 patients as false negative (FN), which gave a sensitivity of 72%, a specificity of 88%, a PPV of 93%, a negative predictive value (NPV) of 62% and an accuracy of 78%. CT recognised in 7 cases a TP result, in 3 cases an FP, in 5 cases a TN and in 11 cases an FN result. This produced a sensitivity of 39%, a specificity of 63%, a PPV of 70%, an NPV of 31% and an accuracy of 46%.ConclusionsThree-phase bone scanning did not deliver any diagnostic benefit, since no result was able to differentiate unequivocally between infection-related and reactive changes. Antigranulocyte scintigraphy using Tc-99m-sulesomab represented a highly suitable technique for diagnostically clarifying combat-related infections of the extremities. It is superior to CT in sensitivity, specificity, PPV, NPV and accuracy.

Antigranulocyte scintigraphy of septic loosening of hip prosthesis: influence of different analyzing methods

Summary Aim: Diagnosis of infection with help of antigranulocyte scintigraphy near body stem is difficult because of contemporary visualisation of bone marrow. Therefore, we investigated, whether it is possible to improve the accuracy in diagnosing septic loosening of hip endoprosthesis by changing the analyzing methods. Methods: In 28 patients, the results of a visual interpretation of late scan, a visual interpretation and a quantitative interpretation of time-activity-course were compared. These results were verified by histology respectively microbiology. Results: Histological and microbiological verification found 14 septic loosening and 14 aseptic loosening of the hip protheses. Therefore, sensitivity, specifity, negative and positive predictive value for the visual interpretation of late scan were 0.86,0.57,0.80 and 0.67. For visual and quantitative interpretation of time-activity-course we found 0.86,0.79,0.85 and 0.80 respectively 1,0.93, 1,0.93. For interobserver agreement we found kappa coefficients of 0.28 ± 0.2 for visual interpretation of late scan, 0.48 ±0.17 for visual interpretation and 1.0 ± 0 for quantitative interpretation of time-activity-course. Conclusion: In all investigated values quantitative interpretation of time-activity-course was superior to the other analyzing methods. Therefore, antigranulocyte scintigraphy for septic loosening of hip endoprosthesis should be interpreted quantitativly.