Sulfonyl-Containing Boronate Caps for Optimization of Biological Properties of 99mTc(III) Radiotracers [99mTcCl(CDO)­(CDOH)2B‑R] (CDOH2 = Cyclohexanedione Dioxime)

In this study, different boronate caps were used to optimize biodistribution properties of radiotracers [99mTcCl­(CDO)­(CDOH)2B-R] (1, R = 3S; 2, R = 3SP; 3, R = 3MS; 4, R = 3DMS; 5, R = 3MSB; 6, R = 3MMS; 7, R = 3MSA; 8, R = 3DMSA; 9, R = 4S; 10, R = 4MS; 11, R = 4MSB). Among the 11 new 99mTc radiotracers, 2 shows the most promising characteristics of an optimal heart imaging agent. Its initial heart uptake is close to that of 99mTc-Teboroxime, but its heart retention time is significantly longer. Its heart/liver, heart/lung, and heart/muscle ratios are also better than those of 99mTc-Teboroxime. The SPECT image quality with 2 in SD rats is better than that with 99mTc-Teboroxime. The high initial heart uptake, long heart retention, and high heart/background ratios make 2 an excellent SPECT radiotracer for MPI.