*2.1.2 Diabetic pedal osteomyelitis*

Because diabetics can have a significant foot infection with few signs or symptoms and without mounting a systemic inflammatory response, the diagnosis of osteomyelitis can easily be overlooked [20]. Molecular imaging has always had an important role in the workup of these patients and data indicate that 18F-FDG is useful in this population. In one meta-analysis, the pooled sensitivity and specificity of 18F-FDG were 74% and 91%, respectively [21].

In another meta-analysis, the pooled sensitivity and specificity of 18F-FDG were 89% and 92%, respectively, which was similar to the pooled sensitivity and specificity of 99mTc-labeled leukocyte scintigraphy: 91% and 92%, respectively [22].

### *2.1.3 Periprosthetic joint infection*

In a systematic review the pooled sensitivity and specificity of 18F-FDG-PET for diagnosing lower extremity periprosthetic joint infection (PJI) were 86% (95% CI: 82−90%) and 86% (95% CI: 83−89%), respectively [23]. In another systematic review, the pooled sensitivity and specificity of 18F-FDG-PET for lower extremity PJI were 82.1% (95% CI: 68.0−90.8%) and 86.6% (95% CI: 79.7−91.4%), respectively [24]. The authors noted that caution is warranted because results of individual studies were heterogeneous and could not be fully explored. These limitations are borne out by the inconsistent results reported in individual investigations over the years [25]. Different test probabilities, the inability to discriminate between infection and aseptic inflammation, and a lack of standardized interpretative criteria are obstacles to incorporating 18F-FDG-PET into the routine diagnostic imaging workup for PJI (**Figure 5**) [26].

Data on 18F-FDG for diagnosing PJI of shoulder arthroplasties are scant. In an investigation of 86 patients with suspected chronic PJI of the shoulder, the sensitivity and specificity of 18F-FDG PET/CT were 14% (3/22) and 91% (58/64), respectively [27].
