99mTc-Tetrofosmin

Fig. 4. Lipophilic-cationic( +1) myocardial perfusion imaging agents A) 99mTc-tetrofosmin R = -CH2CH,0CH,CH3 B), 9"Tc = sestamibi R=C=NCH,C (OCHJ (CH,), Q 99mTc-furifosmin R = -CH2CH2OCH2CH3...

Myoview 99mTc-tetrofosmin (67) is another clinically approved, lipophilic, cationic perfusion agent (286). The molecule contains trans-... 

Fig. 14 Time variation of a heart/lung and b heart/liver ratios for the complexes 99mTcN-DBODC (squares), 99mTc-Sestamibi (circles) and 99mTc-Tetrofosmin (triangles) measured at a specific time after injection in rats. The values are expressed as the ratio between the activity localized in the heart and the activity localized in the lungs and the liver, respectively...

A comparative study of transport kinetics between [ Tc]MIBI and [ Tc]Tetrofosmin in drug-sensitive cells and its resistant counterparts demonstrated that functional activity of Pgp can be detected with equal sensitivity with both radiotracers. The steady-state accumulation of [ " Tc]Tetrofosmin in a human epidermoid carcinoma cell line KB 3-1 (59.4 3.0 fmol/mg protein) and its colchicine-resistant derivative KB 8-5 (1.9 0.06 fmol/mg protein) were approximately half of the values obtained for [ Tc]MIBI in the same cells (104.6 4.1 and 2.85 0.1 fmol/mg protein, respectively). Nevertheless the ratio of cell accumulation (KB 3-1/KB 8-5) for [ Tc]Tetrofosmin (43.7) was similar to that obtained for [ Tc]MIBI (37.4), suggesting that both tracers could detect Pgp expression with the same efficacy. The lower cellular accumulation of [ Tc]Tetrofosmin compared with [ Tc]MIBI was systematically reported in independent studies with different resistant cell lines [68,75], a fact that is probability related with the individual characteristics of each radiotracer. In fact, despite having similar characteristics, these tracers are not identical. [99mTc]Tetrofosmin is less sensitive than [ Tc]MIBI to the electric transmembrane potentials generated in living cells. Moreover, whereas [ Tc]MIBI accumulates preferentially in mitochondria, [ Tc]Tetrofosmin remains in cytoplasm and only a small part is sequestered in mitochondria. 

Yapar Z, Kibar M, Ozbarlas S, Yapar AF, Uguz A, Zorludemir S et al. 99mTc-tetrofosmin scintigraphy in musculoskeletal tumours the relationship between P-glyco-protein expression and tetrofosmin uptake in malignant lesions. Nucl Med Commtm 2002 23 991 1000. 

Figure 7.12 (A) 99mTc-sestamibi (Cardiolite ) and (B) "mTc-tetrofosmin (Myoview ).

Zaret BL, Rigo P, Wackers FJTH, et al. The Tetrofosmin International Trial Study Group Myocardial perfusion imaging with 99mTc-tectrofosmin. Comparison to... 

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