Fossheim S L, Kellar K E, Mansson S, Colet J M, Rongved P, Fahlvik A K, Klaveness J
Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, Norway.
J Magn Reson Imaging. 1999 Feb;9(2):295-303. doi: 10.1002/(sici)1522-2586(199902)9:2<295::aid-jmri22>3.0.co;2-l.
Gadolinium and dysprosium diethylenetriamine pentaacetic acid-labeled starch microparticles (Gd-DTPA-SP and Dy-DTPA-SP) were investigated as model liver contrast agents. The liver contrast efficacy of particles with low and high metal contents was compared in two imaging models: in vivo rat liver and ex vivo perfused rat liver. The biodistribution of intravenously injected particles was also assessed by ex vivo relaxometry and inductively coupled plasma atomic emission spectrophotometry of tissues. All particles reduced the liver signal intensity on T2-weighted spin-echo and gradient-recalled echo images as a result of susceptibility effects. Because of their higher magnetic susceptibility, the Dy-DTPA-SP were more effective negative contrast enhancers than the Gd-DTPA-SP. On T1-weighted spin-echo images, only the Gd-DTPA-SP with low metal content significantly increased the liver signal intensity. In addition, these low-loading Gd-DTPA-SP markedly reduced the blood T1. The two latter observations were not consistent with the anticipated blood circulation time of microparticles, but were a result of the lower stability of these particles in blood compared with Gd-DTPA-SP, which has a high metal content. Regardless of stability or imaging conditions, the paramagnetic starch particles investigated showed potential as negative liver contrast enhancers. However, the observed accumulation of particles in the lungs represented a biological limitation for their use as contrast agents.
钆和镝二乙烯三胺五乙酸标记的淀粉微粒（Gd-DTPA-SP和Dy-DTPA-SP）被作为肝脏对比剂模型进行研究。在两种成像模型中比较了低金属含量和高金属含量微粒的肝脏对比效果：体内大鼠肝脏和离体灌注大鼠肝脏。还通过离体弛豫测量法和组织的电感耦合等离子体原子发射光谱法评估了静脉注射微粒的生物分布。由于磁化率效应，所有微粒在T2加权自旋回波和梯度回波图像上均降低了肝脏信号强度。由于Dy-DTPA-SP具有更高的磁化率，因此它比Gd-DTPA-SP是更有效的阴性对比增强剂。在T1加权自旋回波图像上，只有低金属含量的Gd-DTPA-SP能显著增加肝脏信号强度。此外，这些低负载量的Gd-DTPA-SP显著降低了血液T1。后两个观察结果与微粒预期的血液循环时间不一致，而是由于这些微粒在血液中的稳定性低于高金属含量的Gd-DTPA-SP所致。无论稳定性或成像条件如何，所研究的顺磁性淀粉微粒都显示出作为阴性肝脏对比增强剂的潜力。然而，观察到的微粒在肺中的蓄积是其作为对比剂使用的生物学限制。
