Buckenmaier Kai, Rudolph Matthias, Fehling Paul, Steffen Theodor, Back Christoph, Bernard Rebekka, Pohmann Rolf, Bernarding Johannes, Kleiner Reinhold, Koelle Dieter, Plaumann Markus, Scheffler Klaus
High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Max-Planck-Ring 11, 72076 Tübingen, Germany.
Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany.
Rev Sci Instrum. 2018 Dec;89(12):125103. doi: 10.1063/1.5043369.
Ultralow-field (ULF) nuclear magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) are promising spectroscopy and imaging methods allowing for, e.g., the simultaneous detection of multiple nuclei or imaging in the vicinity of metals. To overcome the inherently low signal-to-noise ratio that usually hampers a wider application, we present an alternative approach to prepolarized ULF MRS employing hyperpolarization techniques like signal amplification by reversible exchange (SABRE) or Overhauser dynamic nuclear polarization (ODNP). Both techniques allow continuous hyperpolarization of H as well as other MR-active nuclei. For the implementation, a superconducting quantum interference device (SQUID)-based ULF MRS/MRI detection scheme was constructed. Due to the very low intrinsic noise level, SQUIDs are superior to conventional Faraday detection coils at ULFs. Additionally, the broadband characteristics of SQUIDs enable them to simultaneously detect the MR signal of different nuclei such as C, F, or H. Since SQUIDs detect the MR signal directly, they are an ideal tool for a quantitative investigation of hyperpolarization techniques such as SABRE or ODNP.
超低场（ULF）核磁共振波谱（MRS）和磁共振成像（MRI）是很有前景的波谱和成像方法，例如，它们能够同时检测多个原子核或在金属附近进行成像。为了克服通常会阻碍更广泛应用的固有低信噪比问题，我们提出了一种采用诸如可逆交换信号放大（SABRE）或奥弗豪泽动态核极化（ODNP）等超极化技术的预极化ULF MRS替代方法。这两种技术都能使氢以及其他具有磁共振活性的原子核持续超极化。为了实现这一目标，构建了一种基于超导量子干涉装置（SQUID）的ULF MRS/MRI检测方案。由于其极低的固有噪声水平，在超低场下，SQUID优于传统的法拉第检测线圈。此外，SQUID的宽带特性使其能够同时检测不同原子核（如碳、氟或氢）的磁共振信号。由于SQUID直接检测磁共振信号，它们是定量研究诸如SABRE或ODNP等超极化技术的理想工具。
