Fig. 2

Patient (case # 1) with a history of right hip prosthesis implantation performed 7 months before imaging. The results of ¹⁸F-FDG PET/CT (upper two rows) and ⁶⁸Ga-citrate PET/CT (lower two rows) are presented. a–f The red arrows clearly indicate ¹⁸F-FDG uptake occurring at the sinus tract, which was absent on the corresponding ⁶⁸Ga-citrate PET/CT image. There was also evidence of swollen periarticular soft tissue (blue arrows) at the right ischiofemoral space on CT, which was accompanied by an increased ¹⁸F-FDG uptake. A similar pattern of radiotracer uptake (b, h) was found to occur at the bone-prosthesis interface of the stem component, as well as in the adjacent soft tissue. The imaging results were considered positive, and the case was subsequently classified as true positive. g–l The green arrows indicate an increased ⁶⁸Ga-citrate uptake occurring at the left femoral shaft. The CT scan revealed cortical hypertrophy caused by a prior traumatic fracture followed by bone reunion