Dual-tracer approach vs. dual time-point approach in leukocyte scintigraphy in treatment evaluation of persistent chronic prosthetic joint infection

Both dual time-point (99m)Tc-hexamethylpropylene amine oxime (HMPAO)-leukocyte scintigraphy and dual-tracer (99m)Tc-HMPAO-leukocyte scintigraphy (with the addition of (99m)Tc-nanocolloid bone marrow scintigraphy) have been used to diagnose prosthetic joint infection (PJI). A treatment evaluation of persistent PJI using these imaging protocols has yet to be presented. OBJECTIVE: The purpose of this study was to compare the accuracy of dual time-point (99m)Tc-HMPAO-leukocyte scintigraphy to the dual-tracer alternative of single time-point (99m)Tc-HMPAO-leukocyte scintigraphy or single-photon emission computed tomography/computed tomography (SPECT/CT) combined with a (99m)Tc-nanocolloid bone marrow scintigraphy or SPECT/CT, for treatment evaluation of PJI. MATERIAL AND METHODS: Thirty-one PJI patients under antibiotic treatment were included in this retrospective study. Examinations were organized into three settings. Setting one used dual time-point approach with delayed (2 h) and late (24 h) planar (99m)Tc-HMPAO-leukocyte scintigraphy, including both visual and semiquantitative analysis. Setting two used delayed (2 h) planar (99m)Tc-HMPAO-leukocyte scintigraphy combined with (99m)Tc-nanocolloid bone marrow scintigraphy and for setting three SPECT/CT replaced planar imaging. RESULTS: Accuracy was 0.68 for visual evaluation and 0.55 for semiquantitative evaluation of setting one; 0.71 for setting two; and 0.68 for setting three. Sensitivity was 0.54 for visual evaluation and 0.31 for semiquantitative evaluation of setting one; 0.38 for setting two; and 0.46 for setting three. Specificity was 0.78 for visual evaluation and 0.72 for semiquantitative evaluation of setting one; 0.94 for setting two; and 0.83 for setting three. CONCLUSION: No significant difference in accuracy, sensitivity, or specificity between the approaches for treatment evaluation of suspected persistent PJI in the hip or knee was observed.