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

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 accurac y in diagnosing septic loosening of hip endoprosthesis by changing the anal yzing methods. Methods. In 28 patients, the results of a visual interpretat ion of late scan, a visual interpretation and a quantitative interpretation of time-activity-course were compared. These results were verified by hist ology respectively microbiology. Results: Histological and microbiological verification found 14 septic loosening and 14 aseptic loosening of the hip protheses. Therefore, sensitivity, specific negative and positive predictiv e value for the visual interpretation of late scan were 0.86, 0.57, 0.80 an d 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 inter observer agreement we found kappa coefficients of 0.28 +/- 0.2 for visual i nterpretation of late scan, 0.48 +/- 0.17 for visual interpretation and 1.0 +/- 0 for quantitative interpretation of time-octivity-course. Conclusion: In all investigated values quantitative interpretation of time-activity-co urse was superior to the other analyzing methods. Therefore, antigranulocyt e scintigraphy for septic loosening of hip endoprosthesis should be interpr eted quantitativly.