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FIGURE 1. 18F-FDG (left), WBC (middle), and marrow (right) images. (A) Infected 9-mo-old cemented left hip hemiarthroplasty. The only periprosthetic activity present on 18F-FDG image is at neck of femoral component, a nonspecific finding. Spatially incongruent activity (arrowheads) on WBC/marrow study is consistent with infection. (B) A 13-y-old hybrid right total hip prosthesis, with aseptic loosening of acetabular component. On 18F-FDG image, nonspecific periprosthetic activity is present along neck of femoral component and extends around acetabular component. Note similarity in appearance to that of infected hip prosthesis in A. WBC/marrow study is negative for infection. (C) There is nonspecific synovial activity on 18F-FDG image of infected 5-y-old cemented left total knee replacement. Femoral component was loose; tibial component was fixed. WBC/marrow study shows spatially incongruent distribution of activity in left knee, consistent with infection. (D) There is nonspecific synovial activity on 18F-FDG image of 10-y-old cemented left total knee replacement, with aseptic loosening of both femoral and tibial components. Uptake pattern is similar to that in C. WBC/marrow study is negative for infection.
