Fossheim S, Johansson C, Fahlvik A K, Grace D, Klaveness J
Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, Norway.
Magn Reson Med. 1996 Feb;35(2):201-6. doi: 10.1002/mrm.1910350211.
The T2* contrast efficacy of paramagnetic contrast agents is dependent on their magnetic properties. Vibrating sample magnetometry (VSM) and the Live Chan NMR method have been used to evaluate the influence of ligand structure on the bulk magnetic susceptibility (BMS) of low-molecular weight (LMW) lanthanide chelates. VSM was also used for the BMS assessment of LMW lanthanide chelates covalently attached to cross-linked starch particles. The ligand structure had no influence on the BMS of the gadolinium (Gd) and dysprosium (Dy) chelates. The mean BMS value of the Dy-chelates was 1.8 fold higher than that of the Gd-chelates. The holmium (Ho) DTPA-BMA chelate had a similar BMS to that of Dy-DTPA-BMA while the lowest BMS was found for europium (Eu(III)) DTPA-BMA. The covalent attachment of Gd-DTPA and Dy-DTPA to a cross-linked starch particle had no impact on their intrinsic magnetic properties. The BMS data were in good accordance with those obtained for non-particulate bound LMW Dy- and Gd-chelates. The magnetic susceptibility of the Gd-DTPA labeled particles was described by the Curie law, indicative of no magnetic interactions between Gd-DTPA molecules. The magnetic susceptibility of the Dy-DTPA labeled particles followed the Curie-Weiss law with a Curie-Weiss temperature of about-2 K, indicating magnetic interactions. The magnetic susceptibility of Dy-DTPA will, however, not be affected by such magnetic interactions at physiological temperatures.
顺磁性造影剂的T2*对比效能取决于其磁特性。振动样品磁强计（VSM）和实时通道核磁共振方法已被用于评估配体结构对低分子量（LMW）镧系螯合物的体积磁化率（BMS）的影响。VSM还用于对共价连接到交联淀粉颗粒上的LMW镧系螯合物进行BMS评估。配体结构对钆（Gd）和镝（Dy）螯合物的BMS没有影响。Dy螯合物的平均BMS值比Gd螯合物高1.8倍。钬（Ho）DTPA - BMA螯合物的BMS与Dy - DTPA - BMA相似，而铕（Eu(III)）DTPA - BMA的BMS最低。Gd - DTPA和Dy - DTPA与交联淀粉颗粒的共价连接对其固有磁特性没有影响。BMS数据与非颗粒结合的LMW Dy和Gd螯合物的数据非常一致。Gd - DTPA标记颗粒的磁化率由居里定律描述，表明Gd - DTPA分子之间没有磁相互作用。Dy - DTPA标记颗粒的磁化率遵循居里 - 外斯定律，居里 - 外斯温度约为 - 2K，表明存在磁相互作用。然而，在生理温度下，Dy - DTPA的磁化率不会受到这种磁相互作用的影响。
