Comparative study of arterial vulnerable plaque molecular imaging with novel molecular probes 99Tcm-Duramycin and 99Tcm-RGD in rabbit models

Objective To investigate the potential of 99Tcm-Duramycin and 99Tcm-RGD in detecting vulnerable plaque in rabbit models. Methods Fifteen healthy New Zealand male rabbits were randomly divided into group A (control group, n=5), group B (stable plaque group, n=5) and group C (vulnerable plaque group, n=5). Animals were injected with 99Tcm-Duramycin and 99Tcm-RGD at the end of 4, 8 and 12 weeks. SPECT/CT scanning was performed at 0.5 h post injection. One rabbit was sacrificed at the end of 4 weeks and one at the end of 8 weeks after imaging. The others were sacrificed at the end of 12 weeks after imaging studies. All aortas were collected. Intravascular ultrasound (IVUS) was performed at the end of 8, 12 weeks before SPECT/CT scanning. The data was analyzed with paired t test. Results In group A, the aortas had little uptake of the two probes. In group B, the aortas showed obvious radioactive uptake of 99Tcm-Duramycin and 99Tcm-RGD at the end of 8 weeks and 12 weeks, while 99Tcm-Duramycin gave better display than 99Tcm-RGD. In group C, 99Tcm-Duramycin uptake was higher than 99Tcm-RGD uptake in the aorta. The T/NT ratios of 99Tcm-Duramycin and 99Tcm-RGD in group C were 2.14±0.34 and 1.46±0.34 (t=4.072, P<0.05) at the end of 4 weeks, 2.93±0.41 and 1.66±0.22 (t=5.578, P<0.05) at the end of 8 weeks, 3.25±0.29 and 1.81±0.28 (t=19.692, P<0.05) at the end of 12 weeks. In isolated specimen of group C, the yellow lipid plaque of the intima bulged on the lumen at the end of 12 weeks. IVUS indicated that, at the end of 8 weeks and 12 weeks, the endometrial thickness of group C was (450±104) mm and (767±52) mm (t=44.024, P<0.05) respectively, and the rates of luminal stenosis were (29.30±2.81)% and (37.98±6.41)% (t=9.226, P<0.05). Conclusions Both 99Tcm-Duramycin and 99Tcm-RGD may be used to detect vulnerable plaque at early time. 99Tcm-Duramycin may detect vulnerable atherosclerotic plaque earlier than 99Tcm-RGD and provide better diagnostic image. Key words: Plaque, atherosclerotic; Molecular imaging; Tomography, emission-computed, single-photon; Tomography, X-ray computed; Ultrasonography, interventional; Arg-Gly-Asp; Duramycin; Rabbits