中文摘要：

目的：评价两性离子修饰超微超顺磁氧化铁（USPIO）在1.5T、3.0T的体外弛豫率及动物体内的血管成像中的效果。方法：USPIO的合成反应在单模微波化学合成仪中进行,并经两性离子进行表面修饰。将各对比剂在纯水溶液中稀释后分别于1.5T及3.0T进行扫描。测量图像信号后计算各对比剂的弛豫率。18只新西兰白兔分为3组,分别在1.5T及3.0T进行血管成像,ZM、SH U 555 C剂量均为40μmol Fe/kg,Gd-DTPA为0.2 mmol/kg。测算腹主动脉的信噪比及对比噪声比。各个时间点对比剂组间SNR、CNR差异的比较使用方差分析,若差异有统计学意义则进一步使用最小显著差法进行两两比较。结果：1.5T、R1和R2从低到高的顺序为Gd-DTPA、ZM和SHU 555 C;3.0T,其顺序为Gd-DTPA和SHU 555 C、ZM,而两磁场中R2/R1比值由高到低均为SH U 555 C、ZM和Gd-DTPA。1.5T 3组对比剂首过成像时信噪比及对比噪声比无显著差异（P=0.258及P=0.314）。从15 min开始,ZM组显著优于其余2组。而3.0T前3时相,Gd-DTPA效果较优,ZM成像效果与SHU 555 C相似。从5 min开始,ZM成像效果显著优于其余2组。结论：ZM血浆半衰期长,在1.5T及3.0T弛豫率高,平衡期磁共振血管成像效果显著优于其余2种对比剂。

英文摘要：

Objective：To evaluate Rl and R2 of zwitterionic nanoparticles and magnetic resonance angiography（MRA） in vitro in comparison with Gd-DTPA and SHU 555 C at 1.5 and 3T.Methods：The nanoparticles were synthesized by a microwave assisted polyol process in which zwitterionic structure was introduced onto the surface of this particle.Decreasing concentrations of various contrast agents in pure water solution were evaluated with 1.5 and 3T clinical scanners.Signal intensity measurements were used to calculate T1 and T2 relaxation times of all samples.MRA at 1.5 and 3.0 T were performed in eighteen Male New Zealand rabbits before and after contrast agent administration at multiple time points at 40μmol Fe/kg body weight of ZM and SH U 555 C and 0.2mmol/kg body weight of Gd-DTPA.SNR and CNR were measured and calculated at the abdominal aorta.For different field strength,SNR and CNR were statistically evaluated by using the analysis of variance test and LSD was used for pairwise comparison.Results：At 1.5T,the order of R1 and R2 from low to high was Gd-DTPA,ZM,SHU 555 CR2/R1 of SH U 555 C was highest,ZM declined,R2/R1 of Gd-DTPA was the lowest.At 3.OT,the order of Rl and R2 from high to low were ZM.SHU 555 C and Gd-DTPA,R2/R1 of SH U 555 C was highest,ZM declined,R2/R1 of Gd-DTPA was the lowest.At 1.5T,there was no significant different among SNR and CNR of Gd-DTPA,SHU 555 C and ZM at first-pass phase（P = 0.258 and P = 0.314）.From 15 minutes to 2 hour,SNR and CNR of ZM were higher than these of the rest two groups.At 3.0T,At first to third time point,SNR and CNR of Gd-DTPA were highest,ZM was better than or equal to SHU 555 C.From 5 minutes to 2 hour,SNR and CNR of ZM were higher than those of the rest two groups（P〈0.05）.Conclusions;ZM with mild positive charge has long blood half-life and high relaxivity in 1.5 and 3.0T.MRA with ZM is superior to SHU 555 C and Gd-DTPA,especially in equilibrium phase.