Table 1. Diagnostic criteria for prosthetic joint infection in different imaging studies and pathological/microbiological evaluation.

Name of the test	Diagnostic criteria for prosthetic joint infection
FDG-PET	Study was called positive for infection if increased FDG uptake was noted at the prosthesis-bone interface in the middle portion of the shaft of the hip prosthesis. Study was considered negative if FDG uptake was limited to the soft tissues, or adjacent only to the neck of the prosthesis. For the patients with knee arthroplasty, only uptake at the bone/prosthesis interface was considered as being consistent with infection. Patients with no or minimal uptake in these locations were interpreted to have non-infected joints
WBC/BM imaging	WBC/BM scans were read as positive for infection if radiotracer activity was noted in peri-prosthetic region on the WBC images and no corresponding radiotracer activity was observed on the BM images. The combined scans were read as negative for infection if the radiotracer uptake distribution from the two techniques were similar and spatially congruent.
Pathological/microbiological evaluation	All pathologic sections were investigated using standard hematoxylin and eosin staining techniques. Sections were analyzed according to the criteria as described by Feldman et al. [16]: (1) presence of granulation tissue; (2) utilization of the five most cellular fields for final diagnosis, as determined on the basis of the number of polymorphonuclear (PMN) leukocytes; (3) cell count determination under 40-times magnification; (4) utilization of at least two samples of tissue; and (5) inclusion of only PMN leukocytes, identified within tissue rather than fibrin, with well-defined cytoplasmic borders. Frozen specimens with fewer than five PMN leukocytes per high-power field were considered aseptic, while specimens with at least ten PMN cells indicated infection. Specimens with five to nine PMN leukocytes raised suspicion for infection, leaving culture reports in this equivocal group to determine the final diagnosis. A permanent specimen was considered positive if five or more PMN leukocytes per high power field were noted.