Comparison of fluorotyrosines and methionine uptake in F98 rat gliomas

The transport mechanisms of O-(2-[18F]fluoroethyl)-L-tyrosine (FET) and 2-[18F]fluoro-L-tyrosine (FTyr) were compared to those of [3H]-Methyl-L-methionine (MET) in F98 rat glioma cells in vitro and by tumor imaging by ex vivo dual tracer autoradiography in F98 rat gliomas. Both, FET and FTyr exhibited similar transport characteristics in F98 glioma cells compared to MET, i.e. mainly a sodium dependent transport similar to system B0,+ and sodium independent transport via system L. Radioactivity of FET in the acid precipitable fraction was <1% after 120 min incubation time while FTyr and MET exhibited a 15-18% incorporation into proteins. Comparison of FET and FTyr with MET uptake in F98 rat gliomas demonstrated a significant correlation of tumor to brain ratios and a similar intratumoral tracer distribution pattern