Abstract
Quick methods are functional in clinical practice in order to ensure the fastest availability of radiopharmaceuticals. For this purpose, we investigated the radiochemical purity of the widely used 99mTc-HMDP (hydroxymethylene diphosphonate), 99mTc-HMPAO (hexamethylpropyleneamine oxime) and 99mTc-Tetrofosmin by reducing time as compared to the manufacturer’s method. Methods: We applied a miniaturized chromatographic method with a reduced strip development from 18 cm to 9 cm for all three radiopharmaceuticals. The specific support media and solvent system of manufacturer’s methods was kept unchanged for 99mTc-HMDP and 99mTc-Tetrofosmin while for 99mTc-HMPAO the ITLC polysilicic gel (ITLC-SA) was replaced with a monosilicic gel (ITLC-SG) in the chromatographic system that uses methyl ethyl ketone (MEK) as solvent. The method was applied and compared to the routine ITLC insert method in a total of 30 batches for each radiopharmaceutical. The precision of repeated tests was determined by comparison with the results of 10 replications on the same batch. Small volume of concentrated 99mTcO4, and 99mTc-albumin nanocolloid were used to produce potential radiochemical impurities. Correlation between the quick methods and the insert methods was analyzed using a non-parametric two tiled test and a 2 x 2 contingency table with the associated Fisher exact test was used to evaluate sensibility and specificity. A ROC analysis was performed to evaluate the best cut off. Results: The % of radiochemical purity (RCP) of the quick methods agree with the standard chromatography procedures. We found that 99mTcO4 and colloidal impurities are not the only common radiochemical impurities with 99mTc-tetrofosmin and strip development reduction of ITLC manufacturer’s method will worsen system’s resolution and may produce potential inaccuracy. Conclusion: The miniaturized methods we described represent a fast and reliable alternative for 99mTc-Exametazime and 99mTc-Oxidronate quality control with the upper cut off for acceptable RCP values of 84%, 95% respectively. For 99mTc-Tetrofosmin RCP testing a longer strip as described in the standard method is warrant.