Topic
Hyperpolarization (physics)
About: Hyperpolarization (physics) is a research topic. Over the lifetime, 1261 publications have been published within this topic receiving 41240 citations.
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TL;DR: The method can be used generally for signal enhancement and reduction of measurement time in liquid-state NMR and opens up for a variety of in vitro and in vivo applications of DNP-enhanced NMR.
Abstract: A method for obtaining strongly polarized nuclear spins in solution has
been developed. The method uses low temperature, high magnetic field, and
dynamic nuclear polarization (DNP) to strongly polarize nuclear spins in the
solid state. The solid sample is subsequently dissolved rapidly in a suitable
solvent to create a solution of molecules with hyperpolarized nuclear spins.
The polarization is performed in a DNP polarizer, consisting of a
super-conducting magnet (3.35 T) and a liquid-helium cooled sample space. The
sample is irradiated with microwaves at ≈94 GHz. Subsequent to
polarization, the sample is dissolved by an injection system inside the DNP
magnet. The dissolution process effectively preserves the nuclear
polarization. The resulting hyperpolarized liquid sample can be transferred to
a high-resolution NMR spectrometer, where an enhanced NMR signal can be
acquired, or it may be used as an agent for in vivo imaging or
spectroscopy. In this article we describe the use of the method on aqueous
solutions of [ 13 C]urea. Polarizations of 37% for 13 C and
7.8% for 15 N, respectively, were obtained after the dissolution.
These polarizations correspond to an enhancement of 44,400 for 13 C
and 23,500 for 15 N, respectively, compared with thermal equilibrium
at 9.4 T and room temperature. The method can be used generally for signal
enhancement and reduction of measurement time in liquid-state NMR and opens up
for a variety of in vitro and in vivo applications of
DNP-enhanced NMR.
2,508 citations
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1,806 citations
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TL;DR: Tissue pH can be imaged in vivo from the ratio of the signal intensities of hyperpolarized bicarbonate and 13CO2 following intravenous injection of hyperPolarized H13CO3-.
Abstract: As alterations in tissue pH underlie many pathological processes, the capability to image tissue pH in the clinic could offer new ways of detecting disease and response to treatment. Dynamic nuclear polarization is an emerging technique for substantially increasing the sensitivity of magnetic resonance imaging experiments. Here we show that tissue pH can be imaged in vivo from the ratio of the signal intensities of hyperpolarized bicarbonate (H(13)CO(3)(-)) and (13)CO(2) following intravenous injection of hyperpolarized H(13)CO(3)(-). The technique was demonstrated in a mouse tumour model, which showed that the average tumour interstitial pH was significantly lower than the surrounding tissue. Given that bicarbonate is an endogenous molecule that can be infused in relatively high concentrations into patients, we propose that this technique could be used clinically to image pathological processes that are associated with alterations in tissue pH, such as cancer, ischaemia and inflammation.
768 citations
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TL;DR: It is shown here that a metal complex can facilitate the reversible interaction of para-hydrogen with a suitable organic substrate such that up to an 800-fold increase in proton, carbon, and nitrogen signal strengths are seen for the substrate without its hydrogenation.
Abstract: The sensitivity of both nuclear magnetic resonance spectroscopy and magnetic resonance imaging is very low because the detected signal strength depends on the small population difference between spin states even in high magnetic fields. Hyperpolarization methods can be used to increase this difference and thereby enhance signal strength. This has been achieved previously by incorporating the molecular spin singlet para-hydrogen into hydrogenation reaction products. We show here that a metal complex can facilitate the reversible interaction of para-hydrogen with a suitable organic substrate such that up to an 800-fold increase in proton, carbon, and nitrogen signal strengths are seen for the substrate without its hydrogenation. These polarized signals can be selectively detected when combined with methods that suppress background signals.
737 citations
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University of California, San Francisco1, University of Cambridge2, Vanderbilt University3, École Polytechnique Fédérale de Lausanne4, Sunnybrook Health Sciences Centre5, University of Texas Southwestern Medical Center6, University of York7, Institute of Cancer Research8, Center for Devices and Radiological Health9, University of Pennsylvania10, Duke University11
TL;DR: The known abnormalities in cancer metabolism, the value and limitations of current imaging methods for metabolism, and the principles of hyperpolarization are summarized.
661 citations