Journal of Isotopes (Aug 2022)
Preparation and Preliminary Imaging Evaluation of a Group of Novel Rapid 99mTc-Labeled Boric Acid Derivatives Tracers for Myocardial Perfusion Imaging
Abstract
Nuclear cardiology plays an important role in management of cardiac patients with known or suspected coronary artery disease (CAD). CAD is the leading cause of premature death and permanent disability. Myocardial perfusion imaging (MPI) with radiotracers is a non-invasive technique that shows the heart function and the areas of perfusion defects. In order to evaluate perfusion defects accurately, the radiotracer used in MPI studies must be taken up into myocardium in proportion to the regional myocardial blood flow. At present, 99mTc-TEBO is commonly used in clinic for rapid myocardial perfusion imaging, which has high initial uptake but poor myocardial retention, so it is necessary to optimize its structure. In this study, a group of novel 99mTc-labeled rapid boric acid derivatives tracers for myocardial perfusion imaging, including 99mTc-2SP, 99mTc-4LPA and 99mTc-2MDM were prepared in this study. The preparation time of these tracers was 30 min, and all of them were colorless clear liquid. The radiochemical purity of the three tracers was > 95%, respectively. The above tracer agents were used to perform SPECT dynamic imaging in healthy miniature pigs and compared with 99mTc-TEBO. After 99mTc-TEBO injection, rapid uptake was shown in left ventricular myocardium within 0.5 min, but the myocardial radioactivity decreased rapidly to about 75% of the peak value and the ratio of the radioactivity between myocardium/blood pool was 1.63 at 10 min. Compared with 99mTc-TEBO, 99mTc-2SP had prolonged retention and slower elution in myocardium within 15 min after the injection when the 2-methylsulfonyl pyridine-5-boric acid group was introduced into the 99mTc-2SP structure. The myocardial radioactivity still maintained 95% of the peak value, and the ratio of radioactivity between myocardium/blood pool was 3.75, which was significantly higher than that of 99mTc-TEBO. However, the other two imaging agents 99mTc-4LPA and 99mTc-2MDM showed poor uptake in myocardium within 15 min after injection. In conclusion, 99mTc-2SP was an ideal boric acid derivatives tracers for myocardial perfusion imaging and has prospect for clinical application in future.
