“…51 In addition, the correlation between FDG uptake and tumor grading is fairly weak for the majority of tumors; only gliomas, sarcomas, and thyroid cancers demonstrate strong correlations. 15,52,53 To make matters more complicated, some benign tumors, such as giant cell tumors, juvenile pilocytic astrocytomas, and Warthin tumors, frequently demonstrate intense FDG uptake. [54][55][56] Thus, although FDG uptake is modulated by several factors that often serve as poor prognostic markers, such as hypoxia, increased cellular proliferation, and the activation of a variety of oncogenes, the multifactorial etiology of increased FDG uptake limits its ability to assess for parameters other than glucose metabolism and may explain the variable success of FDG as a prognostic marker.…”