CXCR4 and neoplasm: [68Ga]Pentixafor was shown to have variable uptake characteristics in gliomas, the tumor SUVs were less than those of 18F-FET (although brain background was very low), and there was an inconsistent relationship between [68Ga]Pentixafor uptake and CXCR4 immunohistochemistry on resected tumor tissue [21].