[(18)F]FPEB and [(18)F]FDEGPECO comparative study of mGlu5 quantification in rodent brain

The aim of this study is to compare [(18)F]FPEB and [(18)F]FDEGPECO for the quantification of mGlu5 receptors in rodent brains. After preparation of radioligands, dynamic PET data was acquired for 90min. Estimated non-displaceable binding potential (BPND) values were calculated from the non-invasive Logan's graphical analysis method. Although both radioligands showed similar radiochemical amenability, [(18)F]FPEB PET showed higher brain uptake and superior binding potential values than those of [(18)F]FDEGPECO PET (peak brain uptakes in the hippocampus and the striatum: 7.2-8.7 vs. 5.0-6.2, BPND: 7.3-9.6 vs. 0.3-0.4 for [(18)F]FPEB and [(18)F]FDEGPECO, respectively). In addition, the target-to-reference ratios for [(18)F]FPEB is >4 fold than those of [(18)F]FDEGPECO. From this evidence, we conclude that [(18)F]FPEB is a superior radioligand for mGlu5 imaging in preclinical studies.