December 04, 1991 - December 04, 2024

  • Date:28ThursdayOctober 2021

    Zoom: “Fast, accessible hyperpolarization for MRI and liquid-state NMR”

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    09:30 - 10:30
    Ilai Schwartz
    NVision Imaging Technologies, Ulm
    Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy
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    Nuclear spin hyperpolarization provides a promising route to overcome the challenges imposed by the limited sensitivity of nuclear magnetic resonance. Significant progress in the last decades was achieved by the development of new hyperpolarization techniques (e.g. dissolution-DNP). This has resulted in the demonstration of new MRI applications utilizing hyperpolarized 13C nuclei in metabolic probes as well as promising results in hyperpolarized liquid state NMR. However, hyperpolarization for both MRI and liquid state NMR applications is still a challenging endeavor, requiring expensive hardware and imposing limitations on the experimental setup.

    In this talk I will present our latest developments for achieving fast, accessible polarization for both MRI and NMR applications utilizing a variety of polarization techniques: (1) For MRI applications we have demonstrated for the first time that using parahydrogen induced polarization (PHIP), hyperpolarized fumarate and pyruvate can be prepared at clinically relevant concentrations (> 100mM) and hyperpolarization values up to 20% at the time of injection. In a comparative study we show that PHIP based methods can compete and even surpass both polarization and concentration levels of metabolic tracers prepared by DNP but at a fraction of the cost, complexity and preparation time. (2) Leveraging optical polarization, we developed a technique for versatile liquid state NMR hyperpolarization, achieving between 200- and 1730-fold signal enhancement at 1.45T for a range of small molecules. The signal enhancement is induced by using optically polarized pentacene-doped naphthalene crystals as a source of spin polarization. We demonstrate that rapid dissolution of the highly polarized crystal enables transfer of polarization to the target molecules via intermolecular cross relaxation in the liquid state at room temperature. Due to the extremely high magnetization of the naphthalene molecules, the cross relaxation leads to a substantial polarization buildup in the target analytes. Crucially, the polarization transfer is achieved without costly instrumentation and occurs in less than a minute inside the NMR spectrometer