TY - JOUR

T1 - Imaging of Biomolecular NMR Signals Amplified by Reversible Exchange with Parahydrogen Inside an MRI Scanner

AU - Kovtunov, Kirill V.

AU - Kidd, Bryce E.

AU - Salnikov, Oleg G.

AU - Bales, Liana B.

AU - Gemeinhardt, Max E.

AU - Gesiorski, Jonathan

AU - Shchepin, Roman V.

AU - Chekmenev, Eduard Y.

AU - Goodson, Boyd M.

AU - Koptyug, Igor V.

N1 - Publisher Copyright: © 2017 American Chemical Society.

PY - 2017/11/22

Y1 - 2017/11/22

N2 - The signal amplification by reversible exchange (SABRE) technique employs exchange with singlet-state parahydrogen to efficiently generate high levels of nuclear spin polarization. Spontaneous SABRE has been shown previously to be efficient in the milli-Tesla and micro-Tesla regimes. We have recently demonstrated that high-field SABRE is also possible, where proton sites of molecules that are able to reversibly coordinate to a metal center can be hyperpolarized directly within high-field magnets, potentially offering the convenience of in situ hyperpolarization-based spectroscopy and imaging without sample shuttling. Here, we show efficient polarization transfer from parahydrogen (para-H2) to the 15N atoms of imidazole-15N2 and nicotinamide-15N achieved via high-field SABRE (HF-SABRE). Spontaneous transfer of spin order from the para-H2 protons to 15N atoms at the high magnetic field of an MRI scanner allows one not only to record enhanced 15N NMR spectra of in situ hyperpolarized biomolecules but also to perform imaging using conventional MRI sequences. 2D 15N MRI of high-field SABRE-hyperpolarized imidazole with spatial resolution of 0.3 × 0.3 mm2 at 9.4 T magnetic field and a high signal-to-noise ratio (SNR) of ∼99 was demonstrated. We show that 1H MRI of in situ HF-SABRE hyperpolarized biomolecules (e.g., imidazole-15N2) is also feasible. Taken together, these results show that heteronuclear (15N) and 1H spectroscopic detection and imaging of high-field-SABRE-hyperpolarized molecules are promising tools for a number of emerging applications.

AB - The signal amplification by reversible exchange (SABRE) technique employs exchange with singlet-state parahydrogen to efficiently generate high levels of nuclear spin polarization. Spontaneous SABRE has been shown previously to be efficient in the milli-Tesla and micro-Tesla regimes. We have recently demonstrated that high-field SABRE is also possible, where proton sites of molecules that are able to reversibly coordinate to a metal center can be hyperpolarized directly within high-field magnets, potentially offering the convenience of in situ hyperpolarization-based spectroscopy and imaging without sample shuttling. Here, we show efficient polarization transfer from parahydrogen (para-H2) to the 15N atoms of imidazole-15N2 and nicotinamide-15N achieved via high-field SABRE (HF-SABRE). Spontaneous transfer of spin order from the para-H2 protons to 15N atoms at the high magnetic field of an MRI scanner allows one not only to record enhanced 15N NMR spectra of in situ hyperpolarized biomolecules but also to perform imaging using conventional MRI sequences. 2D 15N MRI of high-field SABRE-hyperpolarized imidazole with spatial resolution of 0.3 × 0.3 mm2 at 9.4 T magnetic field and a high signal-to-noise ratio (SNR) of ∼99 was demonstrated. We show that 1H MRI of in situ HF-SABRE hyperpolarized biomolecules (e.g., imidazole-15N2) is also feasible. Taken together, these results show that heteronuclear (15N) and 1H spectroscopic detection and imaging of high-field-SABRE-hyperpolarized molecules are promising tools for a number of emerging applications.

KW - MAGNETIC-RESONANCE

KW - PARA-HYDROGEN

KW - N-15 HYPERPOLARIZATION

KW - INDUCED POLARIZATION

KW - SABRE

KW - AMPLIFICATION

KW - FEASIBILITY

KW - ENHANCEMENT

KW - SENSITIVITY

KW - COMPLEXES

UR - http://www.scopus.com/inward/record.url?scp=85035096584&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.7b10549

DO - 10.1021/acs.jpcc.7b10549

M3 - Article

C2 - 30701013

AN - SCOPUS:85035096584

VL - 121

SP - 25994

EP - 25999

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 46

ER -