Evaluation of F-18-labeled amino acid derivatives and [18F]FDG as PET probes in a brain tumor-bearing animal model.
2-Deoxy-2-[(18)F]fluoro-d-glucose ([(18)F]FDG) has been extensively used as positron emission tomography (PET) tracer in clinical tumor imaging. This study compared the pharmacokinetics of two (18)F-labeled amino acid derivatives, O-2-[(18)F]fluoroethyl-l-tyrosine (l-[(18)F]FET) and 4-borono-2-[(18)F]fluoro-l-phenylalanine-fructose (l-[(18)F]FBPA-Fr), to that of [(18)F]FDG in an animal brain tumor model.


METHODS
A self-modified automated PET tracer synthesizer was used to produce no-carrier-added (nca) l-[(18)F]FET. The cellular uptake, biodistribution, autoradiography and microPET imaging of l-[(18)F]FET, l-[(18)F]FBPA-Fr and [(18)F]FDG were performed with F98 glioma cell culture and F98 glioma-bearing Fischer344 rats.


RESULTS
The radiochemical purity of l-[(18)F]FET was >98% and the radiochemical yield was 50% in average of 16 runs. The uptake of l-[(18)F]FET and l-[(18)F]FBPA-Fr in the F98 glioma cells increased rapidly for the first 5 min and reached a steady-state level after 10 min of incubation, whereas the cellular uptake of [(18)F]FDG kept increasing during the study period. The biodistribution of l-[(18)F]FET, l-[(18)F]FBPA-Fr and [(18)F]FDG in the brain tumors was 1.26+/-0.22, 0.86+/-0.08 and 2.77+/-0.44 %ID/g at 60 min postinjection, respectively, while the tumor-to-normal brain ratios of l-[(18)F]FET (3.15) and l-[(18)F]FBPA-Fr (3.44) were higher than that of [(18)F]FDG (1.44). Both microPET images and autoradiograms of l-[(18)F]FET and l-[(18)F]FBPA-Fr exhibited remarkable uptake with high contrast in the brain tumor, whereas [(18)F]FDG showed high uptake in the normal brain and gave blurred brain tumor images.


CONCLUSIONS
Both l-[(18)F]FET and l-[(18)F]FBPA-Fr are superior to [(18)F]FDG for the brain tumor imaging as shown in this study with microPET.
Wang
Hsin-Ell
HE
Institute of Radiological Sciences, National Yang-Ming University, Taipei 112, Taiwan. hewang@ym.edu.tw
Wu
Shih-Yen
SY
Chang
Chi-Wei
CW
Liu
Ren-Shen
RS
Hwang
Li-Chung
LC
Lee
Te-Wei
TW
Chen
Jyh-Cheng
JC
Hwang
Jeng-Jong
JJ
D000818:Animals; D001896:Boron Compounds / Q000493:pharmacokinetics*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005910:Glioma / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006020:Glycopeptides / Q000493:pharmacokinetics*; D008657:Metabolic Clearance Rate; D015336:Molecular Probe Techniques; D009928:Organ Specificity; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D014018:Tissue Distribution; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
C504600:4-borono-2-fluorophenylalaninefructose; D001896:Boron Compounds; D005462:Fluorine Radioisotopes; D006020:Glycopeptides; C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D014443:Tyrosine