CSF3 and infection: No physiological uptake is noted in bone itself (unless free 18F-fluoride is present as a contaminant), but bone marrow uptake can be present to a variable degree in patients receiving growth factors (granulocyte colony-stimulating factor, G-CSF, and granulocyte macrophage CSF, GM-CSF) as well as in patients with marrow proliferation for other reasons such as infection, inflammation or anaemia, and following chemotherapy.Due to the high physiological FDG uptake in the brain, FDG PET/CT is of limited value for detection of brain metastases.