Medicine technetium

Since that time nuclear reactors around the world have produced hundreds of isotopes of most of the elements in the periodic table. As discussed in Chapter 13, some of these isotopes are used daily in nuclear medicine. Technetium-99m is a gamma ray emitter used daily in hospitals. Tc-99m is produced from the beta decay of molybdenum-99 as shown in the following reaction ... 

Technetium-99m coordination compounds are used very widely as noniavasive imaging tools (35) (see Imaging technology Radioactive tracers). Different coordination species concentrate ia different organs. Several of the [Tc O(chelate)2] types have been used. In fact, the large majority of nuclear medicine scans ia the United States are of technetium-99m complexes. Moreover, chiral transition-metal complexes have been used to probe nucleic acid stmcture (see Nucleic acids). For example, the two chiral isomers of tris(1,10-phenanthroline)mthenium (IT) [24162-09-2] (14) iateract differentiy with DNA. These compounds are enantioselective and provide an addition tool for DNA stmctural iaterpretation (36). 

Recent advances in technetium chemistry bridging inorganic chemistry and nuclear medicine. E. Deutsch and K. Libson, Comments Inorg. Chem., 1984,3, 83-103 (30). 

Nuclear medicine scans Method of body imaging that uses a radioactive tracer material (e.g., technetium and gallium) to produce body images. For example, bone scans detect uptake and cellular activity in areas of inflammation. 

Nuclear reactions involving technetium have been actively studied until today. Our interest in the nuclear chemistry of technetium is based on various reasons. Technetium was the first artificially produced element in the periodic table, a weighable amount of technetium ("Tc) is now available, and 99mTc is one of the most important radionuclides in nuclear medicine. In addition, technetium is an element of importance from a nuclear safety point of view. 

Nicolini M, Bandoli G, Mazzi U (eds) (1986) Technetium in chemistry and nuclear medicine 2, Cortina International, Verona/Raven, New York... 

Acknowledging the important part that 99mTc(V) radiopharmaceuticals are playing in nuclear medicine, advances in their coordination chemistry, as attained by new syntheses and better structural characterization, are discussed with respect to the design of Tc(V) radiotracers. In the light of current interest in making technetium complexes active in vivo, a chapter considering several aspects of reactivity is included. 

Until the mid 1970s, technetium(V) had been widely ignored and its chemistry misinterpreted. Then, the development of the chemistry of technetium(V) was prompted by the trends and needs of nuclear medicine, which predominantly uses technetium-99m radiopharmaceuticals for a broad range of diagnostics. 

The O-donor complexes of Tc(V) exhibit moderate and differential stability in aqueous solution. In the presence of reducing agents, such as stannous chloride, they are reduced to mainly undefined products of Tc in a lower oxidation state. However, at the low technetium concentration of "mTc that is used in nuclear medicine, the rate of the reduction process is very low. This makes it possible to prepare Tc(V) radiopharmaceuticals with O-donor ligands by the usual procedure, in which an excess of reducing agent over technetium is unavoidably used. The Tc(V) complexes also tend either to be easily oxidized or to disproportionate [23],... 

Before complexes can be used in nuclear medicine, especially for brain function studies, in vivo reactivity has to be imposed upon them. Retention in the brain is necessary for perfusion imaging. This can be achieved by substituents on the ligand that bind them to binding sites in the brain. N-alkylation with methyl and other alkyl groups led to the class of complexes shown in Fig. 19. Upon complexation to technetium, the IV-alkyl substituent can assume a syn or anti configuration with respect to the oxo ligand, as proved by X-ray crystal... 

Davison A (1983) In Deutsch E, Nicolini M, Wagner HN Jr (eds) Technetium in chemistry and nuclear medicine, Cortina International, Verona, p 3... 

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