Comparison of Measurement Method for Radiochemical Purity Determination of 99mTc-Methoxy Isobutyl Isonitrile

Globally, the death prevalence from heart disease accounts for 9.4 million deaths a year and will have predicted by 2030 increased to 23.6 million people suffering from heart disease. To solving this problem not only focus on treatment the disease but we should also think how to preventing it. Cardiac diagnosis has been recognized since 1989 using technetium-99m-methoxy isobutyl isonitrile (99mTc-MIBI) radiopharmaceutical. Since 2012, Indonesia has been producing about 500 vials MIBI kits (precursor of 99mTc-MIBI) per year. Since radiolabeling of MIBI kit with 99mTc is performed in hospital, therefore the quality control (QC) of the resulted product (99mTc-MIBI) should be performed at the
hospital as well. The extraction method is a simple, fast, and friendly used method for determining radiochemical purity (RCP) of 99mTc-MIBI. However, this method still has some weaknesses as the sample volume and type of measurement tools greatly influence the results. Therefore, the aim of this study is to compare the results of RCP measurements of 99mTc-MIBI used by extraction method which is then measured with a dose calibrator (DC) and a gamma counter (GC), as well as thin layer chromatography (TLC) method. The research involved radiolabeling MIBI kit with 99mTc, testing RCP with TLC standard, DC and GC methods, and then comparing RCP 99mTc-MIBI results in those three methods with statistical calculation. The chromatogram resulted from TLC method showed 99mTc-MIBI (Rf 1.0) nicely separate from its impurities 99mTcO2 (Rf 0.0) and 99mTcO4-free (Rf 0.4 – 0.6). Minimum sample volume that can be well measured on DC and GC tools on extraction method is 250µL. The percentages of RCP of 99mTc-MIBI measured using TLC, DC, and GC methodsare 97.84 ± 0.49%, 97.45 ± 0.53%, and 97.95 ± 0.64% respectively. Comparison of extraction method with two different measurement tools, dose calibrator and gamma counter, was found not significantly different based on statistical calculation with t-value of 1.98. In addition, comparison between thin layer chromatography and gamma
counter was found not also significantly different either with t-value of 0.46. Based on the above-mentioned results it can be concluded that the extraction method using two type tools, dose calibrator and gamma counter, do not differ significantly with the standard method TLC.