Department of Radiology, Medical Physics, Medical Center, University of Freiburg, Faculty of Medicine, Germany.
Phys Chem Chem Phys. 2021 Jan 28;23(3):2320-2330. doi: 10.1039/d0cp06281b.
The signal enhancement provided by the hyperpolarization of nuclear spins of metabolites is a promising technique for diagnostic magnetic resonance imaging (MRI). To date, most 13C-contrast agents are hyperpolarized utilizing a complex or cost-intensive polarizer. Recently, the in situ parahydrogen-induced 13C hyperpolarization was demonstrated. Hydrogenation, spin order transfer (SOT) by a pulsed NMR sequence, in vivo administration, and detection was achieved within the magnet bore of a 7 Tesla MRI system. So far, the hyperpolarization of the xenobiotic molecule 1-13C-hydroxyethylpropionate (HEP) and the biomolecule 1-13C-succinate (SUC) through the PH-INEPT+ sequence and a SOT scheme proposed by Goldman et al., respectively, was shown. Here, we investigate further the hyperpolarization of SUC at 7 Tesla and study the performance of two additional SOT sequences. Moreover, we present first results of the hyperpolarization at high magnetic field of 1-13C-phospholactate (PLAC), a derivate to obtain the metabolite lactate, employing the PH-INEPT+ sequence. For SUC and PLAC, 13C polarizations of about 1-2% were achieved within seconds and with minimal equipment. Effects that potentially may explain loss of 13C polarization have been identified, i.e. low hydrogenation yield, fast T1/T2 relaxation and the rarely considered 13C isotope labeling effect.
代谢物核自旋的超极化提供的信号增强是诊断磁共振成像（MRI）的一种很有前途的技术。迄今为止，大多数 13C 对比剂都是利用复杂或昂贵的极化器来实现超极化的。最近，人们已经证明了原位 para 氢诱导的 13C 超极化。在 7T MRI 系统的磁体腔内实现了加氢、通过脉冲 NMR 序列进行自旋顺序转移（SOT）、体内给药和检测。到目前为止，通过 PH-INEPT+序列和 Goldman 等人提出的 SOT 方案，分别展示了外源性分子 1-13C-羟乙基丙酸酯（HEP）和生物分子 1-13C-琥珀酸（SUC）的极化。在这里，我们进一步研究了在 7T 下 SUC 的超极化，并研究了两种附加 SOT 序列的性能。此外，我们还首次展示了采用 PH-INEPT+序列对衍生代谢物乳酸的 1-13C-磷酸乳酸盐（PLAC）在高磁场下的超极化结果。对于 SUC 和 PLAC，在几秒钟内实现了约 1-2%的 13C 极化，所需设备最少。已经确定了可能导致 13C 极化损失的潜在影响因素，即加氢产率低、T1/T2 弛豫快以及很少考虑的 13C 同位素标记效应。
