Experimental study of SPECT imaging with novel myocardial perfusion imaging tracer: 99Tcm-3SPboroxime / 中华核医学与分子影像杂志

ABSTRACT

Objective@#To assess the superiority of 99Tcm-3SPboroxime (99Tcm-3SP for short) as a fast-myocardial perfusion imaging (MPI) tracer in normal and acute myocardial infarction (AMI) mini-swine.@*Methods@#99Tcm-3SP and 99Tcm-Teboroxime (99Tcm-TEBO for short) were prepared. Approximately 370 MBq 99Tcm-3SP or 99Tcm-TEBO was injected intravenously in 2 healthy mini-swine separately. Dynamic planar images were acquired immediately after injection and continued for 20 min using a standard SPECT camera. The radioactivity uptakes in the heart, liver, and lungs were measured, and heart/liver and heart/lung ratios over time were calculated. Dynamic SPECT studies were performed in 4 normal swine and 1 AMI-swine using cadmium zinc telluride-SPECT (CZT-SPECT). List mode acquisitions were immediately started and continued for 15 min after intravenous injection of approximately 370 MBq 99Tcm-TEBO and 99Tcm-3SP. The injection of two radiotracers in the same swine was completed within 2 d. The radioactivity uptakes in heart and liver were measured, and heart/liver ratio was calculated. Image quality was also evaluated. Paired t test was used to analyze the data.@*Results@#The radiochemical purity of 99Tcm-TEBO or 99Tcm-3SP were both above 95%. The initial heart uptake of 99Tcm-3SP was very close to that of 99Tcm-TEBO (planar image, 2 min postinjection: 309.32×103 vs 314.13×103 counts/MBq; SPECT image, 2 min postinjection (corrected): 7.96±0.87 vs 8.24±1.53, t=0.277, P>0.05), but the myocardial retention time was much longer than that of 99Tcm-TEBO (planar image, 20 min postinjection: 218.67×103 vs 143.19×103 counts/MBq; SPECT image, 15 min postinjection (corrected): 6.76±0.45 vs 5.06±0.33, t=-12.412, P=0.001). The uptake of liver and heart/liver ratio between 99Tcm-TEBO and 99Tcm-3SP were similar (t values: -1.332-1.101, all P>0.05 within 15 min). SPECT MPI images demonstrated uniform tracer distribution with clearly visualizable myocardial boundary in normal myocardium and intense perfusion defect in infarct myocardium. High quality SPECT images could be obtained in any of the 5 min imaging windows over the first 15 min after injection of 99Tcm-3SP in normal swine and AMI-swine.@*Conclusion@#99Tcm-3SP is a promising 99Tcm-labeled radiotracer for fast-MPI considering its high heart uptake, long myocardial retention time (20 min postinjection) and superior SPECT image quality.