ABSTRACT
The purpose of this study was to synthesize and evaluate the necrosis target of MRI contrast agent based on rhein.The novel ligand 10-{ [6-(1,8-dihydroxyanthraquinone-3-carboxamido) hexyl] amino} acetyl-1,4,7,10-tetraazacyclododecan-1,4,7-triacetic acid (DO3A-rhein) was synthesized by two-step acylation and two-step deprotection.The paramagnetic contrast agent gadolinium 10-{ [6-(1,8-dihydroxyanthraquinone-3-carboxamido) hexyl] amino} acetyl-1,4,7,10-tetraazacyclododecan-1,4,7-triacetate (Gd-DO3A-rhein) was obtained by coordination of Gd3+ with the synthesized ligand.Its necrosis affinity was evaluated by liver infarction and muscular necrosis on rat models.The MRI was performed before administration of Gd-DO3A-rhein and during 0 h to 12 h after administration of Gd-DO3A-rhein (0.1 mmol/kg),respectively,and Gd-DOTA was used as control.After MRI scanning,rats were sacrificed and necrotic tissues were stained using triphenyltetrazolium chloride (TTC) and hematoxylin-eosin (HE).MRI images of liver infarction and muscular necrosis on rat models showed significantly enhanced signal intensity compared with normal tissues.The contrast ratios of necrotic liver/normal liver were 1.61 ±0.14 and 2.36 ±0.20 at 3 h and 12 h postinjection of Gd-DO3A-rhein (0.1 mmol/kg) respectively,demonstrating a significant difference compared with pre-administration of Gd-DO3A-rhein (1.16 ±0.10;P ＜ 0.05).The same results were obtained from necrotic muscles.These findings suggested that Gd-DO3A-rhein possessed the necrosis target and imaging capability of necrotic tissues.
ABSTRACT
@#The purpose of this study was to evaluate the necrosis target and imaging potential of necrotic myocardium of 131I-emodin and 131I-emodic acid. The iodogen coating method was used to radioiodinate emodin and emodic acid with iodine-131. Mice model of muscular necrosis and rat model of myocardial infarction(MI)were established to evaluate the necrosis affinity and imaging potential of 131I-emodin and 131I-emodic acid. Mice were sacrificed at 2, 12 and 24 h after injection respectively. The radioactive uptake in major organs and necrotic muscle were calculated by a γ-counter. At 6 h after administration, SPECT/CT imaging of necrotic myocardium in rats, biodistribution detection, histopathological analysis were applied to evaluate their necrosis affinity and imaging potential. The results of biodistribution from mice demonstrated that 131I-emodin and 131I-emodic acid showed peculiar necrosis target and exhibited an obvious clearance of radioactivity from normal organs. On SPECT/CT images, relatively high uptake as a hot spot was shown in the heart of the model rat, while no obvious uptake was observed in the heart of the control rat. The radioactivity ratios of necrotic to normal myocardium of 131I-emodin and 131I-emodic acid amounted up to 9. 72 and 13. 14 by quantitative autoradiography analysis, respectively. These results suggested that 131I-emodin and 131I-emodic acid possess the necrosis target and imaging potential of necrotic myocardium.