title: Test-retest reproducibility of the metabotropic glutamate receptor 5 ligand [¹⁸F]FPEB with bolus plus constant infusion in humans.
abstract: OBJECTIVE
  [(18)F]FPEB is a promising PET radioligand for the metabotropic glutamate receptor 5 (mGluR5), a potential target for the treatment of neuropsychiatric diseases. The purpose of this study was to evaluate the test-retest reproducibility of [(18)F]FPEB in the human brain.
  
  
  METHODS
  Seven healthy male subjects were scanned twice, 3 - 11 weeks apart. Dynamic data were acquired using bolus plus infusion of 162 ± 32 MBq [(18)F]FPEB. Four methods were used to estimate volume of distribution (V T): equilibrium analysis (EQ) using arterial (EQA) or venous input data (EQV), MA1, and a two-tissue compartment model (2 T). Binding potential (BP ND) was also estimated using cerebellar white matter (CWM) or gray matter (CGM) as the reference region using EQ, 2 T and MA1. Absolute test-retest variability (aTRV) of V T and BP ND were calculated for each method. Venous blood measurements (C V) were compared with arterial input (C A) to examine their usability in EQ analysis.
  
  
  RESULTS
  Regional V T estimated by the four methods displayed a high degree of agreement (r (2) ranging from 0.83 to 0.99 among the methods), although EQA and EQV overestimated V T by a mean of 9 % and 7 %, respectively, compared to 2 T. Mean values of aTRV of V T were 11 % by EQA, 12 % by EQV, 14 % by MA1 and 14 % by 2 T. Regional BP ND also agreed well among the methods and mean aTRV of BP ND was 8 - 12 % (CWM) and 7 - 9 % (CGM). Venous and arterial blood concentrations of [(18)F]FPEB were well matched during equilibrium (C V = 1.01 · C A, r (2) = 0.95).
  
  
  CONCLUSIONS
  [(18)F]FPEB binding shows good TRV with minor differences among analysis methods. Venous blood can be used as an alternative for input function measurement instead of arterial blood in EQ analysis. Thus, [(18)F]FPEB is an excellent PET imaging tracer for mGluR5 in humans.
authors.affiliation: PET Center, Department of Diagnostic Radiology, Yale School of Medicine, 801 Howard Avenue, PO Box 208048, New Haven, CT, 06520-8048, USA, angela.park@yale.edu.
authors.forename: Eunkyung
authors.initials: E
authors.lastname: Park
authors.forename: Jenna M
authors.initials: JM
authors.lastname: Sullivan
authors.forename: Beata
authors.initials: B
authors.lastname: Planeta
authors.forename: Jean-Dominique
authors.initials: JD
authors.lastname: Gallezot
authors.forename: Keunpoong
authors.initials: K
authors.lastname: Lim
authors.forename: Shu-Fei
authors.initials: SF
authors.lastname: Lin
authors.forename: Jim
authors.initials: J
authors.lastname: Ropchan
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: McCarthy
authors.forename: Yu-Shin
authors.initials: YS
authors.lastname: Ding
authors.forename: Evan D
authors.initials: ED
authors.lastname: Morris
authors.forename: Wendol A
authors.initials: WA
authors.lastname: Williams
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Huang
authors.forename: Richard E
authors.initials: RE
authors.lastname: Carson
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D009570:Nitriles / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D049268:Positron-Emission Tomography / Q000379:methods*; D011725:Pyridines / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics; D064529:Receptor, Metabotropic Glutamate 5 / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D055815:Young Adult
chemical_list: C527000:3-fluoro-5-((pyridin-3-yl)ethynyl)benzonitrile; C578935:GRM5 protein, human; D009570:Nitriles; D011725:Pyridines; D019275:Radiopharmaceuticals; D064529:Receptor, Metabotropic Glutamate 5