[Methodological study on preparation of a novel myocardial perfusion imaging agent: 99mTc-Q3]

This study was intended to explore the methods of preparing technetium-99m-N, N'-ethylenebis (acetylacetoneiminato) bis [tris (3-methoxy-1-propyl) phosphine] (99mTc-Q3) as a newer cationic myocardial perfusion imaging agent. The optimum scheme of technetium labeling on the basis of exploring the effects of differently labeled conditions on radiochemical purity was established by a multivariate orthogonal experimental design. A newer agent for myocardial perfusion imaging was developed based on the optimum scheme by a stannous chloride reduction method. Preparation, separation, purification and quality control were performed by a chromatography. Experiments for stability (in vitro), sterility, apyrogen, safeness, and for imaging in animals were carried out. "A2B2C2" was chosen as the optimum scheme of this labeled complex. There each of A, B and C factors has significant effect on the radiochemical purity, and there is no one-class cross effect on the radiochemical purity between them. The labeling efficiency and radiochemical purity were measured over 99% labeled 10 min later (at R. T.). The stability (in vitro) was good and kept up to 4 hr or testing (range: 92%-99.37%). The prepared product was sterile, apyrogenic and safe. The scintigraphic imaging in rabbits demonstrated that the tracer accumulated early in the heart and the myocardial imaging displayed clearly up to 3 hr. The results of this methodological study demonstrate that not only high quality 99mTc-Q3 can be obtained but also a standardized procedure for labeling all kinds of 99mTc-agents can be set up, and on this basis, the one-step kit of 99mTc-Q3 may be developed.