Biological Evaluation of L-Tyrosine Labelled with fac-[^99mTc(CO)₃](+) at a para-OH-Coupled 2,3-Diaminopropionic Acid Based Chelator

Radiolabeled amino acids as metabolic tracers are increasingly important for imaging and therapy applications. There are only a few reports on Tc-99m-labeled amino acids that have been evaluated in vivo. In this work we coupled a small and highly potent chelator for the fac-[Tc-99m(CO)(3)](+) core to Ltyrosine through a poly(ethylene glycol) linker and investigated the in vivo biodistribution of the Tc-99m-labeled L-tyrosine derivative. In vivo evaluation and biodistribution in mice bearing C6tumor xenografts revealed little tumor and pancreas uptake. The microSPECT images showed rapid clearance from the blood pool. Fast uptake into the gallbladder and an extended residence time makes this labeled tyrosine suitable for gallbladder imaging and associated dysfunctions.