Recent developments and future aspects of positron emission tomography (PET) in oncology were reviewed and discussed, focusing on the development of new radiopharmaceuticals for cancer imaging and its biological characterization. Because of increased amino acid transport and protein synthesis in cancers, amino acid tracers are useful for cancer imaging. Unlike F-18 FDG, the uptake of amino acid tracers in inflammatory tissues is relatively low compared with that in tumor tissues. We have recently synthesized F-18 fluoromethyltyrosine (F-18 FMT). Biodistribution study and autoradiography (ARG) revealed that its uptake in tumor tissues was sufficiently high with lower uptake in inflammatory tissues and normal organs, except the pancreas. Extracellular matrix proteinase plays an important role in the invasion, metastasis and neovascularization of cancer cells. To measure the enzyme activity in tumors using PET, we developed F-18 SAV03M, which is an inhibitor of matrix metalloproteinase inhibitor. Biodistribution studies revealed that tumor-to-blood and tumor-to-muscle ratios of 2.8 and 13.9, respectively, were obtained 120 min after tracer injection. ARG showed inhomogeneous radioactivity within a tumor, which may reflect an inhomogenous distribution of enzyme activity within a tumor tissue. These results indicate that F-18 FMT and F-18 SAV03M will be promising for in vivo imaging and biological characterization of cancer using PET.
- Matrix metalloproteinase
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