99mTc

Technetium-9 9m sestamibi is used in myocardial perfusion imaging for the evaluation of ischemic heart disease. It is prepared from a lyophilized kit containing tetrakis(2-methoxy isobutyl isonittile) copper(I) tetrafluoroborate stored under nitrogen. Upon reconstitution with up to 5.6 GBq (150 mCi) of 99mTc pertechnetate, the product is formed by boiling for 10 minutes. 

In a similar manner, the existence of (C5H5)Tc(C03) - and of Tc(CsH5)2 was demonstrated for the first time, starting from corresponding organometallic compounds of Mo, which undergoes [) decay to 99mTc. These compounds were also subsequently synthesized -and the chemical properties confirmed. 

M Vidgren, J Arppe, P Vidgren, P Vainio, M Silvasti, H Tukiainen. Pulmonary deposition of 99mTc-labelled salbutamol particles in healthy volunteers after inhalation from a metered-dose inhaler and from a novel multiple-dose powder inhaler. S.T.P. Pharm Sci 4 29-32, 1994. 

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. 

De-excitation of 99mTc has specific features. This nuclide decays with a half-life of 6 hours, but its half-life varies slightly according to environmental conditions [30] or chemical states [31,32], Moreover, the emission probabilities of characteristic X-rays just after the isomeric transition 99mTc — "Tc are influenced by environmental factors [33] which result in a change of the K/VKoc X-ray intensity ratio [34],... 

Fig. 10. A metallocene molecular rocket extracting other metallocenes in neighboring inclusion complexes. As an example 100Ru(y, p) 99mTc reaction, which produces the " TeCp- radical, is shown [43]... 

Analysis of technetium is usually made after chemical separation of the element and it requires a chemical yield tracer (99mTc or 95mTc). These sometimes make... 

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. 

The better known rhenium(V) chemistry is of great interest, not only because it resembles the second-row congener technetium and easily permits non-radio-active model studies for technetium. 186Re and 188Re are attractive isotopes for therapeutic radiopharmaceuticals. 99mTc and 186Re can be considered to be a matched pair for diagnostics and therapy. 

The introduction of metabolizable ester functions may be a very useful means of obtaining retention of the radiotracer within the target, as known for 99mTc-ECD. It may also help to eliminate nontarget radioactivity more rapidly. Therefore, systematic studies have been performed, in order to understand the enzymatic hydrolysis of oxotechnetium(V) complexes with up to four ester groups in the complex [205]. Fig. 30 shows the partial hydrolysis by pig liver esterase as is was observed for 1 2 complexes of derivatized dimercaptosuccinic acid complexes. 

The development of 99mTc-radiopharmaceuticals offers many challenges, since this metal is not a component of any naturally occurring biological... 

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