Prior to the injection, the facet joints have to be defined according to standard radiological techniques (e.g. MRI and physical correlation). Patients are then sent to 18F-Fluoride-PET/MRI imaging, in order to localize facet joints with increased uptake. Facet joints to be injected are again defined according to the location(s) of highest uptake as demonstrated by 18F-Fluoride-PET/MRI.