An untapped potential for imaging of peripheral osteomyelitis in paediatrics using [¹⁸F]FDG PET/CT -the inference from a juvenile porcine model

Purpose: To examine parameters affecting the detection of osteomyelitis (OM) by [ ¹⁸F]FDG PET/CT and to reduce tracer activity in a pig model. Background: [ ¹⁸F]FDG PET/CT is recommended for the diagnosis of OM in the axial skeleton of adults. In children, OM has a tendency to become chronic or recurrent, especially in low-income countries. Early diagnosis and initiation of therapy are therefore essential. We have previously demonstrated that [ ¹⁸F]FDG PET/CT is promising in juvenile Staphylococcus aureus (S. aureus) OM of peripheral bones in a pig model, not failing even small lesions. When using imaging in children, radiation exposure should be balanced against fast diagnostics in the individual case. Methods: Twenty juvenile pigs were inoculated with S. aureus. One week after inoculation, the pigs were [ ¹⁸F]FDG PET/CT scanned. PET list-mode acquired data of a subgroup were retrospectively processed in order to simulate and examine the image quality obtainable with an injected activity of 132 MBq, 44 MBq, 13.2 MBq, and 4.4 MBq, respectively. Results: All lesions were detected by [ ¹⁸F]FDG PET and CT. Some lesions were very small (0.01 cm ³), and others were larger (4.18 cm ³). SUV _max was higher when sequesters (p = 0.023) and fistulas were formed (p < 0.0001). The simulated data demonstrated that it was possible to reduce the activity to 4.4 MBq without compromising image quality in pigs. Conclusions: [ ¹⁸F]FDG PET/CT localized even small OM lesions in peripheral bones. It was possible to reduce the injected activity considerably without compromising image quality, impacting the applicability of PET/CT in peripheral OM in children.