Influence of molecular parameters and increasing magnetic field strength on relaxivity of gadolinium- and manganese-based T1 contrast agents.
Influence of molecular parameters and increasing magnetic field strength on relaxivity of gadolinium- and manganese-based T1 contrast agents.
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DOI：
10.1002/cmmi.267
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发表时间：
2009-03
影响因子：
--
通讯作者：
Uppal, Ritika
中科院分区：
文献类型：
--
作者：
Caravan, Peter;Farrar, Christian T.;Frullano, Luca;Uppal, Ritika
进行模拟，以了解分子参数的相对贡献纵向（r1）和横向（r2）弛豫作为字段的函数，并获得理论弛豫最大值在一定范围内的字段，以了解什么弛豫可以实现实验。测量了一组具有不同分子参数（水交换速率、转动相关时间、水合状态等）的钆和锰配合物的场依赖弛豫率，证实了测量弛豫率与理论一致。先前强调的在低场优化r1的设计原则（非常慢的旋转运动;通过蛋白质结合固定螯合物;优化的水交换速率）不适用于更高的场。在1.5T和更高的磁场下，需要中间旋转相关时间（0.5 - 4 ns），而水交换速率对于实现高r1并不关键。对于靶向应用，建议通过长的柔性接头将金属螯合物的多聚体拴系到蛋白质靶向基团，以使蛋白质的慢运动与结合到金属离子的水分离。对于Gd 3+和Mn 2+络合物，在1.5、3和9.4T下的每离子弛豫率分别为80、45和18 mM− 1 s −1是可行的。
Simulations were performed to understand the relative contributions of molecular parameters to longitudinal (r1) and transverse (r2) relaxivity as a function of field, and to obtain theoretical relaxivity maxima over a range of fields to appreciate what relaxivities can be achieved experimentally. The field dependent relaxivity of a panel of gadolinium and manganese complexes with different molecular parameters: water exchange rates, rotational correlation times, hydration state, etc were measured to confirm that measured relaxivities were consistent with theory. The design tenets previously stressed for optimizing r1 at low fields (very slow rotational motion; chelate immobilized by protein binding; optimized water exchange rate) do not apply at higher fields. At 1.5T and higher fields, an intermediate rotational correlation time is desired (0.5 – 4 ns), while water exchange rate is not as critical to achieving a high r1. For targeted applications it is recommended to tether a multimer of metal chelates to a protein-targeting group via a long flexible linker to decouple the slow motion of the protein from the water(s) bound to the metal ions. Per ion relaxivities of 80, 45, and 18 mM−1s−1 at 1.5, 3, and 9.4T respectively are feasible for Gd3+ and Mn2+ complexes.
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影响因子：
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