Comparative Labelling and Biokinetic Studies of ^99mTc-EDTA(Sn) and ^99mTc-DTPA(Sn)

Summary

Gelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of ^99mTc-EDTA(Sn) and ^99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H₄ and 0.5 (Amol SnCl2 was incubated with 10 ml ^99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of ^99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of ^99mTc-EDTA(Sn) and ^99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for ^99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with ^99mTc-DTPA(Sn) whereas about 60 min was required for ^99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with ^99mTc-EDTA(Sn) but already after 6 min with ^99mTc-DTPA(Sn). The long-term disappearance of ^99mTc-DTPA(Sn) from the kidneys is about five times faster than that for ^99mTc-EDTA(Sn).

• References

• 1 Atkins H. L, Klopper J. F, Eckelman W. C, Richards P. The technetium-99m-DTPA renal study. In Medicial Radioisotope Scintiagraphy 1972, Vol. 2, IAEA, Vienna 1973; 251
• 2 Berman M, Schoenfield R. Invariants in experimental data on linear kinetics and the formulation of models. J. appl. Phys 1956; 27: 1361
• 3 Bianchi C. Measurement of Glomerular Filtration Rate. In Prog. nucl. Med., vol. 2, Editor: Blaufox Karger M. D. Basel and University Park Press Baltimore 1972; 21
• 4 Blaha V, Visek V, Stredova M, Prokopek J. ⁹⁹mTc-EDTA dynamic kidney studies. A comparison with ¹³¹I-Hippuran examinations. In Proc. of IV Int. Symp. Nucl. Med. Karlovy Vary 1975
• 5 Fleay R. F. Technetium-99m-labelled EDTA for renal scanning. Australian Radiology 1968; 12: 256
• 6 Gorski B, Koch H. Über die Komplexbildung von Technetium mit chelatbildenden Liganden-II. J. Inorg. nucl. Chem 1970; 32: 3831
• 7 Kempi V, Persson R. B. R. ^99mTc-DTPA(Sn) dry-kit preparation. Quality control and clearance studies. Nucl. Med. (Stuttg.) 1975; XIII: 389
• 8 Kempi V, Persson R. B. R, Svensson L. Comparative evaluation of ¹³¹I-hippuran and “mTc-DTPA for renal function test. In Proc. of XIII Int. Ann. Meeting Soc. Nucl. Med. (German): Copenhagen; 1975
• 9 Persson R. B. R. Gel-Chromatography-Column-Scan-ning (“GCS”) A method for identification and quality control of technetium-99m radiopharmaceuticals. In Proc. Int. Symp. Radiopharmaceuticals, 1974. Atlanta, Ga., USA. Soc. Nucl. Med. (N.Y.) 1975; 228
• 10 Persson R. B. R, Strand S. E. Labelling processes and short term biodynamical behaviour of different types of Tc-99m labelled complexes. In Radiopharmaceuticals and labelled compounds, Vol. I,IAEA, Vienna 1973; 169
• 11 Persson R. B. R, Strand S. E, Svensson L. A Computer Scintillation camera System for Biokinetic studies of Radiopharmaceuticals (To be published).
• 12 Steigman J, Meinken G, Richards P. The reduction of pertechnetate-99m by stannous chloride-I. The Stoichiometry of the reaction in HCl, in a citrate buffer and in a DTPA buffer. Int. J. appl. Radiat. Isot 1975; 26: 601-609.