Preparation and biological evaluation of 99mTc-CO-MIBI as myocardial perfusion imaging agent

99mTc-Sestamibi has been playing an important role in the cardiac imaging for the last decades. Previously, we reported that [99mTc(CO)3(MIBI)3]+ demonstrated a significant location in myocardium with a lower liver uptake as compared with 99mTc-Sestamibi. In this work, we found that new [99mTc(CO)2(MIBI)4]+ could be prepared with high radiochemical purity. The inter-transformations between [99mTc(CO)3(H2O)(MIBI)2]+, [99mTc(CO)3(MIBI)3]+, and [99mTc(CO)2(MIBI)4]+ were investigated and biodistribution was performed to evaluate the [99mTc(CO)2(MIBI)4]+ as a myocardial perfusion imaging agent. The results showed that one more CO was replaced by MIBI slowing down the pharmacokinetics. The structure characterization was performed on their corresponding rhenium complexes, and the results indicated that there were differences between 99mTc-CO-MIBI and Re-CO-MIBI in preparation and hydrophobic characteristics.