The effect of selected preparation variables on the radiochemical purity of 99mTc-sestamibi.

OBJECTIVE: Measurement of cardiac perfusion via agents such as 99mTc-sestamibi (Cardiolite; DuPont-Merck Pharmaceutical Co., Inc.) is widely used in clinical nuclear medicine for the diagnosis of coronary artery disease. The monograph for 99mTc-sestamibi recommends at least 90% radiochemical purity (RCP) for clinical use. Various factors may influence the RCP of certain reagent kits. Some of these include the amount of activity added to the reagent kit, the generator ingrowth time, the generator manufacturer, the age of the eluate, and the age of the formulated kit. A D-optimal design with a 20-experiment run was devised to study the effects of these variables either alone or in combination on the RCP of 99mTc-sestamibi. METHODS: The RCP was assessed by Baker-Flex thin-layer and high-performance liquid chromatographic methods, immediately and 6 h after reconstitution of the 99mTc-sestamibi. RESULTS: The results showed that 4 of the 5 variables studied were statistically significant predictors of the RCP. The age of the formulated kit did not influence the RCP. CONCLUSION: For any combination of these 4 variables, the mean RCP remained greater than or equal to 90%, that is, within the recommended range of RCP for clinical use at radioactivity levels ranging from 5,550 MBq to 37,000 MBq.