O-(2 - [~ (18) F] Fluoroethyl)-l-tyrosine, Developed,

Positron emission tomography (PET) which is an important tool for the clinical detection of tumors, has been widely employed all over the world. The development of PET technology can not be independent of the synthesis of good PET imaging agents, and the precondition of the medicament research for PET is the synthesis of radiolabelled medicament. There are many kinds of PET imaging agents. The most commonly used one is 18F-FDG which has been widely used in the diagnosis of tumor, heart and brain illness. However, several recent studies have demonstrated the diagnostic limitations of18F-FDG-PET, such as its low specificity, no uptake in some tumor cells and appreciable uptake in inflammatory lesion. Therefore designing and synthesizing more specific and sensitive tumor imaging agents would be an important research field.In the research of new PET imaging agents, radiolabelled amino acids have been widely studied. 0-(2-[18F]fluoroethyl)-L-tyrosine(L-[18F]FET) is a synthetic PET imaging agent that is not metabolized in cells and does not incorporate into proteins. The increased amino acid transport into malignant cells reflects the increasing amino acid requirement in cancer tissues. The 18F-FET has higher specificity for differentiating inflammatory lesions from tumors, lower uptake in normal tissues, clearer images of brain tumors than those of the 18F-FDGThe aim of the experiment is to synthesize O-(2-[18F]fluoroethyl) -L-tyrosine (L-[18F]FET), get its biodistribution in animal, and observe the absorption in brain and tumor, so that we can judge if it is possible to be a PET tracer for tumors, and to provide anew 18F-labeled amino acid as a PET tracer for PET centers.After a few methods tested, we determined to adopt the synthesis method base on the "one-step reaction" of S. H. Ahn from Korea, that is using N-BOC- (L-Tyr) OMe as the starting compound, to get O-(2-p-TsO- ethyl-L-Tyr)OMe as the precursor for 18F -fluorination, and in the end we can gain the O-(2-[18F]fluoroethyl)-L-tyrosine by using the existing 18F-FDG Auto-synthesizer. After getting the 18F-FET, we had done some animal examinations, it appears to be a very promising agent for the diagnosis of tumors.