The quick identification and precise localization of osteomyelitis (OM) is critical for early initiation of antimicrobial and/or surgical treatment and has a significant impact on patient outcome [78
]. FDG-PET/CT has been evaluated in patients with primary OM extensively, has been shown to offer good sensitivity (>95%) and specificities above 87% [79
], and was found superior to MRI [80
] and other nuclear medicine imaging modalities [81
]. However, used in combination with conventional methods, FDG-PET/CT may have limited additional value in the diagnosis of primary OM. In contrast, FDG-PET/CT may play an important role in patients with chronic OM, especially in those patients with previously documented OM and suspected recurrence, or presenting with symptoms of OM for more than six weeks (chronic OM) [3
]. In children with suspected OM, dissemination in multiple bones has to be kept in mind, for which FDG-PET/CT would be suitable. However, to avoid radiation exposure, pediatricians tend to perform MRI rather than FDG-PET/CT in cases of suspected OM [82
For therapy evaluation in patients with OM, the literature results are hopeful. In a recent retrospective study, FDG-PET/CT had a strong impact on the clinical management (initiation or prolongation of antibiotic therapy or recourse to surgical intervention) in 52% of patients with an infection [83
]. Gemmel et al. highlighted the clinical role of FDG-PET/CT in the diagnosis of spinal infections, especially in patients with contraindications to MRI, and in evaluation of the postoperative spine [84
]. Worth to mention is that in MRI inflammatory changes can be seen long after the disappearance of the infection. For this indication, FDG-PET is probably superior to MRI. In children, FDG-PET/CT was found superior in distinguishing between infection and reparative activity within the musculoskeletal system after treatment for acute OM, and termination of antibiotic treatment for children after acute OM seems justified when laboratory parameters and clinical parameters are normal, and FDG-PET/CT is unsuspicious [85
Despite these results, major limitations exist for the use of FDG-PET/CT in some infectious bone diseases. In general, in patients with infections or inflammation, the bone marrow, at various levels, can show increased uptake. In prosthetic joint infections (PJI), the problem is the generation of artifacts, characterized by artificial FDG uptake adjacent to prostheses, because of the inherent problem of partial volume mapping and overcorrection. In PJI, white blood cell scintigraphy is still the first choice [86
]. Further on, nonspecific FDG uptake may be seen in healing tissues, up to 6 months after surgical intervention [87
]. In the diabetic foot, FDG-PET/CT was found to have a low diagnostic accuracy for OM and cannot replace white blood cell scintigraphy [88
At this moment, evidence-based indications for FDG-PET/CT are primary peripheral bone OM (not post-operative, not in diabetic foot) and suspected spinal infection (spondylodiscitis or vertebral OM, not postoperative; see ) [89
]. In the future, one can expect that FDG-PET/CT will also be used to monitor treatment efficacy, and maybe this technique can provide criteria to decide when the treatment can be stopped safely.
FDG-PET of a patient with spondylodiscitis and involvement of the psoas muscles. (a) Coronal MIP view, (b) fused PET/CT sagittal view, and (c) fused PET/CT transaxial view.