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Synthesis and evaluation of [18F]1-amino-3-fluorocyclobutane-1-carboxylic acid to image brain tumors
T M Shoup1, J Olson, J M Hoffman
1Emory Center for PET, Department of Neurosurgery, Emory University, Atlanta, Georgia 30322, USA.
Unlabelled:
We have developed a new tumor-avid amino acid, 1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC), labeled with 18F for nuclear medicine imaging.
Methods:
[18F]FACBC was prepared with high specific activity (no carrier added [NCA]) and was evaluated for its potential in tumor localization. A comparative study was performed for [18F]FACBC and [18F]2-fluorodeoxyglucose (FDG) in which the uptake of each agent in 9L gliosarcoma (implanted intracerebrally in Fisher 344 rats) was measured. In addition, the first human PET study of [18F]FACBC was performed on a patient with residual glioblastoma multiforme. Quantitative brain images of the patient were obtained by using a Siemens 921 47-slice PET imaging system.
Results:
In the rat brain, the initial level of radioactivity accumulation after injection of [18F]FACBC was low (0.11 percentage injected dose per gram [%ID/g]) at 5 min and increased slightly to 0.26 %ID/g at 60 min. The tumor uptake exhibited a maximum at 60 min (1.72 %ID/g), resulting in a tumor-to-brain ratio increase of 5.58 at 5 min to 6.61 at 60 min. In the patient, the uptake of [18F]FACBC in the tumor exhibited a maximum concentration of 146 nCi/mL at 35 min after injection. The uptake of radioactivity in the normal brain tissue was low, 21 nCi/mL at 15 min after injection, and gradually increased to 29 nCi/mL at 60 min after injection. The ratio of tumor to normal tissue was 6 at 20 min after injection. The [18F]FACBC PET scan showed intense uptake in the left frontal region of the brain.
Conclusion:
The amino acid FACBC can be radiofluorinated for clinical use. [18F]FACBC is a potential PET tracer for tumor imaging.