Wang Steven J, Brechbiel Martin, Wiener Erik C
Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, USA.
Invest Radiol. 2003 Oct;38(10):662-8. doi: 10.1097/01.rli.0000084887.47427.75.
Dendrimer-based magnetic resonance imaging (MRI) contrast agents offer many advantages including high levels of amplification. The objective of this research was to test the adequacy and viability of a new family of dendrimers for use as MRI contrast agents in vitro and in vivo.
Dendrimers based on 1,4-diaminobutane core polypropyleneimine (PPI) generation 2 and ammonia core polyamidoamine dendrimers had the free surface amines conjugated to a diethylenetriaminepentaacetic acid derivative followed by complex formation with gadolinium. Relaxivity measurements were made on an IBM Field Cycling Relaxometer. Biodistribution and pharmacokinetic studies were examined with the radiotracer 153Gd in rats and a counting window of 95 to 105 keV. MRI images were conducted at 4.7 T.
The relaxivity of the PPI agent exceeded that of the corresponding generation polyamidoamine (PAMAM) agent. Uptake occurred in the liver, spleen, and kidney. Pharmacokinetic studies showed a biexponential decay with excretion half-lives of 3 hours and 33.6 days respectively. The agent increased the contrast enhancement, 1 hour after injection, of T1-weighted images by 52%.
This PPI agent resulted in significant contrast signal enhancement. This family of agent may also provide a valuable contrast agent backbone.
基于树枝状大分子的磁共振成像（MRI）造影剂具有诸多优势，包括高放大倍数。本研究的目的是在体外和体内测试一类新型树枝状大分子作为MRI造影剂的适用性和可行性。
以1,4 - 二氨基丁烷为核心的第二代聚丙烯亚胺（PPI）树枝状大分子和以氨为核心的聚酰胺 - 胺树枝状大分子，将其游离表面胺与二乙烯三胺五乙酸衍生物共轭，随后与钆形成络合物。在IBM场循环弛豫仪上进行弛豫率测量。用放射性示踪剂153Gd在大鼠体内进行生物分布和药代动力学研究，计数窗口为95至105 keV。在4.7 T下进行MRI成像。
PPI造影剂的弛豫率超过了相应代数的聚酰胺 - 胺（PAMAM）造影剂。在肝脏、脾脏和肾脏中出现摄取。药代动力学研究显示为双指数衰减，排泄半衰期分别为3小时和33.6天。注射后1小时，该造影剂使T1加权图像的对比增强增加了52%。
这种PPI造影剂导致了显著的对比信号增强。这类造影剂也可能提供一种有价值的造影剂骨架。
