三维对比增强MRA:新型血池型对比剂USPIO与Gd-DTPA对比实验研究

Three-dimensional contrast-enhanced MR angiography: comparison of an ultrasmall superparamagnetic iron oxide blood-pool contrast agent and gadopentetate dimeglumine in rabbits

目的将自行研发的USPIO用于动物行3DCE-MRA,并与Gd-DTPA增强MRA比较,评估USPIO增强MRA成像质量,为其临床应用提供实验证据。方法14只健康雄性新西兰大白兔随机分为两组分别给予USPIO和Gd-DTPA行3D-CEMRA扫描,1周后,待对比剂完全排泄,两组交换行相应对比剂增强扫描。所有扫描在1.5T磁共振扫描仪上完成,采用Cardiac线圈,行3DSPGR序列冠位扫描。使用高压注射器由耳缘静脉注入对比剂。给药前扫描1次观察扫描范围(蒙片),打药同时开始行扫描,共连续扫描9个时相,再分别于5、10、15、20、25、30min重复扫描1次。USPIO使用剂量为0.1mmol/kg体重,Gd-DTPA为0.5mmol/kg体重。结果所有动物均能顺利完成扫描,图像质量显示清楚,通常在第2个时相可得到较好动脉期时相。USPIO和Gd-DTPA均可得到明显的血管增强效果。SI主动脉(t)曲线显示USPIO在血管内信号强度达峰时间与Gd-DTPA相似,但持续时间比后者长,峰值信号强度弱于后者(P<0.05)。SNR(t)和CNR(t)曲线显示,USPIO与Gd-DTPA有交叉,但峰值相近,在后期(10min后)USPIO明显高于Gd-DTPA(P<0.05)。两种对比剂对主动脉及其一级分支显示率并无统计学差异(P>0.05)。在USPIO增强较晚时期,实验动物的静脉及门脉显示较Gd-DTPA增强同时期更加清楚。结论USPIO在安全性,采集时间窗以及可同时动静脉,门脉显影上优于Gd-DT-PA,更适于用作CE-MRA。自制USPIO作为血管对比增强剂具有良好的显像效果。

Objective To compare the intravascular enhancement of an ultrasmall superparamagnetic iron oxide （USPIO） blood-pool contrast agent to gadopentetate dimeglumine （Gd-DTPA） for contrast-enhanced MR angiography （CE-MRA） in rabbits. Methods Fourteen male New Zealand white rabbits were assigned to 2 groups randomly. One of the groups were perform CE-MRA with USPIO or Gd-DTPA, and a week delay, to ensure the excretion of contrast agent, perform the MRA with the other contrast agent. MRA were performed in all the animals with a fast three-dimensional spoiled gradient recalled （SPGR） pulse sequence on a high-resolution GE 1.5T Signa CV/i MR scanner with the cardiac coil. The contrast agent was administrated through the ear venous with high-pressure syringe. All the animals were imaged prior to and 9 times after administration of contrast medium, then the perform was repeated at time 5, 10, 15, 20, 25, 30 minutes. USPIO was injected intravenously at a dose of 0. 1 mmol/kg body weight, and Gd-DTPA was injected intravenously at a dose of 0. 5 mmol/kg. Results All the animals finished the MRA, and satisfactory arterial enhancement were obtained with injection of contrast agent. SIaorta（t） showed that the tendency of USPIO was as same as GdDTPA, but the SI peak of USPIO was lower than GdDTPA （P〈0.05）. SNR（t） and CNR（t） showed that there was a cross of USPIO and Gd-DTPA at the early time, but USPIO was much higher than Gd-DTPA from 10 minutes （P〈0.05）. To view the aorta and the branches, there was no difference between USPIO and Gd-DTPA, Both arterial, venous and portal vein enhancement on delayed acquisitions, and USPIO was much better than Gd-DTPA. Conclusion USPIO is safer, longer acquisition time than Gd-DTPA, which makes it more suitable for CE-MRA.