Koenig S H
IBM T. J. Watson Research Center, Yorktown Heights, New York.
Acta Radiol Suppl. 1990;374:17-23.
The range of compounds, both paramagnetic and ferromagnetic, with potential utility as tracers for enhancing contrast in magnetic resonance imaging is very large. Fortunately, the changes in 1/T1 and 1/T2 of water protons in solution--and ultimately in tissue--induced by these agents arise from variations of only a few physical parameters. In the present work, we first consider the properties of Gd-DTPA2- in solution in some detail, including its effects on both inner and outer sphere relaxation of solvent protons. Then, by varying one or another physical parameter, we derive behavior that characterizes several classes of contrast agents with markedly different properties. These include small macrocycles, such as Gd-DOTA-; larger complexes, including oligomers and conjugates of small paramagnetic complexes with protein; magnetized particles, such as magnetite, as a function of their size; and highly anisotropic porphyrin compounds. Predictions are compared with data from the literature.
作为磁共振成像中增强对比度的示踪剂，具有潜在用途的顺磁性和铁磁性化合物范围非常广泛。幸运的是，这些试剂引起的溶液中——最终在组织中——水质子的1/T1和1/T2变化仅源于少数物理参数的变化。在本工作中，我们首先详细考虑了溶液中Gd-DTPA2-的性质，包括其对溶剂质子内球和外球弛豫的影响。然后，通过改变一个或另一个物理参数，我们得出了表征几类具有明显不同性质的造影剂的行为。这些包括小的大环化合物，如Gd-DOTA-；较大的配合物，包括小顺磁性配合物与蛋白质的低聚物和缀合物；磁化颗粒，如磁铁矿，作为其尺寸的函数；以及高度各向异性的卟啉化合物。将预测结果与文献数据进行了比较。
