T1 nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate-13C
T1 nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate-13C
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DOI：
10.1002/nbm.3749
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发表时间：
2017-09-01
影响因子：
2.9
通讯作者：
Scholl, Timothy J.
中科院分区：
文献类型：
--
作者：
Martinez-Santiesteban, Francisco M.;Thien Phuoc Dang;Scholl, Timothy J.
已经提出使用超极化碳酸氢盐-C-13在组织中进行体内pH绘图作为研究肿瘤生长和治疗以及与pH变化相关的其他病理状况的方法。超极化介质的有限自旋-晶格弛豫时间（T-1）是体内成像的重要限制因素。弛豫时间可以在标准磁场（1.5T，3.0T等）下测量，但是在低场没有这样的数据，在低场T-1值可以明显更短。当药剂从偏振器分配和输送到MRI扫描仪时，需要该信息来确定潜在的偏振损失。本研究的目的是测量T-1分散体从低到临床磁场（0.4 mT至3.0 T）的不同超极化碳酸氢盐制剂先前在文献中提出的体内pH值测量。用动态核极化法对富含13碳的铯和碳酸氢钠样品进行超极化，用快速场循环弛豫仪和3.0T临床MRI系统测量不同样品在不同磁场强度下的T-1值。同时分析了氧化氘作为碳酸氢钠溶解介质的效果。这项研究发现，铯制剂的T-1值略短于钠制剂。然而，碳酸氢铯-C-13的更高溶解度意味着它可以在更高浓度下极化，使用比碳酸氢钠-C-13更少的三苯甲基自由基。该研究还确定，由于较高的粘度和较低的可实现浓度，与碳酸氢铯相比，碳酸氢钠制剂的制备和处理更困难，并且氧化氘显著增加了碳酸氢钠溶液的T-1。最后，本文还研究了pH对碳酸氢铯-C-13自旋-晶格弛豫的影响。
In vivo pH mapping in tissue using hyperpolarized hydrogencarbonate-C-13 has been proposed as a method to study tumor growth and treatment and other pathological conditions related to pH changes. The finite spin-lattice relaxation times (T-1) of hyperpolarized media are a significant limiting factor for in vivo imaging. Relaxation times can be measured at standard magnetic fields (1.5T, 3.0T etc.), but no such data are available at low fields, where T-1 values can be significantly shorter. This information is required to determine the potential loss of polarization as the agent is dispensed and transported from the polarizer to the MRI scanner. The purpose of this study is to measure T-1 dispersion from low to clinical magnetic fields (0.4 mT to 3.0T) of different hyperpolarized hydrogencarbonate formulations previously proposed in the literature for in vivo pH measurements. C-13-enriched cesium and sodium hydrogencarbonate preparations were hyperpolarized using dynamic nuclear polarization, and the T-1 values of different samples were measured at different magnetic field strengths using a fast field-cycling relaxometer and a 3.0T clinical MRI system. The effects of deuterium oxide as a dissolution medium for sodium hydrogencarbonate were also analyzed. This study finds that the cesium formulation has slightly shorter T-1 values compared with the sodium preparation. However, the higher solubility of cesium hydrogencarbonate-C-13 means it can be polarized at greater concentration, using less trityl radical than sodium hydrogencarbonate-C-13. This study also establishes that the preparation and handling of sodium hydrogencarbonate formulations in relation to cesium hydrogencarbonate is more difficult, due to the higher viscosity and lower achievable concentrations, and that deuterium oxide significantly increases the T-1 of sodium hydrogencarbonate solutions. Finally, this work also investigates the influence of pH on the spin-lattice relaxation of cesium hydrogencarbonate-C-13 measured over a pH range of 7 to 9 at 0.47T.