Recycling and Imaging of Nuclear Singlet Hyperpolarization

Pileio, Giuseppe; Bowen, Sean; Laustsen, Christoffer; Tayler, Michael C. D.; Hill-Cousins, Joseph T.; Brown, Lynda J.; Brown, Richard C. D.; Ardenkjær‐Larsen, Jan Henrik; Levitt, Malcolm H.

doi:10.1021/ja312333v

Cited by 100 publications

(122 citation statements)

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“…These two facts suggest a number of interesting uses of singlet order in NMR and MRI spectroscopy. A number of researchers have been indeed exploiting its long lifetime for the purposeof storage of hyperpolarisation [4,5,6,7,8,9,10,11,12]. Hyperpolarisation storage, combined with on-demand accessibility, suggests the use of singlet order as a repository of hyperpolarisation from where the signal enhancement gained by a given hyperpolarisation technique can be repeatedly accessed over a long time (tens of minutes) [12].…”

Section: Introductionmentioning

confidence: 99%

“…A number of researchers have been indeed exploiting its long lifetime for the purposeof storage of hyperpolarisation [4,5,6,7,8,9,10,11,12]. Hyperpolarisation storage, combined with on-demand accessibility, suggests the use of singlet order as a repository of hyperpolarisation from where the signal enhancement gained by a given hyperpolarisation technique can be repeatedly accessed over a long time (tens of minutes) [12]. The long lifetime of singlet order has also been used to study slow motions like diffusion [13,14,15,16,17], flow [17], molecular dynamics [18,19] and ligand binding [20,21,22,23].…”

Section: Introductionmentioning

confidence: 99%

“…Significant studies on the chemical requirements for obtaining long-lived spin order have been also conducted [17,51,52,53,54] with a record lifetime of 70 min for a 13 C-pair [54], 26 min for a 15 N-pair [51], and 10 min for a 1 H-pair [17] demonstrated. The potential use of singlet order in MRI has been discussed and demonstrated [55,12,56,43,17,57]. This paper focuses on the efforts of the author and other groups spent in devising methods to access and manipulate singlet order in systems made by two spins-1/2.…”

Section: Introductionmentioning

confidence: 99%

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Singlet NMR methodology in two-spin-1/2 systems

Pileio

2017

Progress in Nuclear Magnetic Resonance Spectroscopy

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This paper discusses methodology developed over the past 12 years in order to access and manipulate singlet order in systems comprising two coupled spin-1/2 nuclei in liquid-state nuclear magnetic resonance. Pulse sequences that are valid for different regimes are discussed, and fully analytical proofs are given using different spin dynamics techniques that include product operator methods, the single transition operator formalism, and average Hamiltonian theory. Methods used to filter singlet order from byproducts of pulse sequences are also listed and discussed analytically. The theoretical maximum amplitudes of the transformations achieved by these techniques are reported, together with the results of numerical simulations performed using custom-built simulation code.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Singlet NMR methodology in two-spin-1/2 systems

Pileio

2017

Progress in Nuclear Magnetic Resonance Spectroscopy

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“…The population imbalance between the singlet state and the triplet states is called singlet order and is protected against many common relaxation mechanisms [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The relaxation time constant for singlet order is called T S and often exceeds the conventional longitudinal relaxation time T 1 by a large factor [16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Long-lived nuclear spin states in rapidly rotating CH 2 D groups

Elliott

Brown

Dumez

et al. 2016

Journal of Magnetic Resonance

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Although monodeuterated methyl groups support proton long-lived states, hindering of the methyl rotation limits the singlet relaxation time. We demonstrate an experimental case in which the rapid rotation of the CH 2 D group extends the singlet lifetime but does not quench the chemical shift difference between the CH 2 D protons, induced by the chiral environment. Proton singlet order is accessed using Spin-Lock Induced Crossing (SLIC) experiments, showing that the singlet relaxation time T S is over 2 minutes, exceeding the longitudinal relaxation time T 1 by a factor of more than 10. This result shows that proton singlet states may be accessible and long-lived in rapidly rotating CH 2 D groups.

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“…4,5 Furthermore, dissolution-DNP (D-DNP) 6 is increasingly popular in metabolic in vivo studies and MRI since it enables inter alia the detection of anomalous metabolic behavior in tumors. 7−11 The combination of LLSs with DNP 12 and MRI 13 methods has recently been developed for applications on clinical MRI systems. The prototypical LLS is a "singlet state" of a pair of nuclear spins, which corresponds to a population imbalance 14 between the antisymmetric triplet manifold and the symmetric singlet state.…”

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confidence: 99%

Hyperpolarized para-Ethanol

et al. 2015

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ABSTRACT:We show that an imbalance between the populations of singlet (S) and triplet (T) states in pairs of magnetically equivalent spins can be generated by dissolution dynamic nuclear polarization. In partly deuterated ethanol (CD 3 13 CH 2 OD), this T/S imbalance can be transferred by cross-relaxation to observable, enhanced signals of protons and coupled 13 C.I n recent years, long-lived states (LLSs) 1 and dynamic nuclear polarization (DNP) 2,3 have been extensively explored, since they offer novel means to overcome two major limitations of nuclear magnetic resonance (NMR), namely the short lifetime of nuclear magnetization (usually limited by the longitudinal relaxation time constant T 1 ) and the low intrinsic sensitivity of NMR and magnetic resonance imaging (MRI) that is normally governed by Boltzmann's law. LLS can preserve spin order over intervals much longer than T 1 : this unique property is attractive for in vivo studies since it represents a promising way to use long-lived NMR signals of metabolites and characterize slow reactions that take place in tissues of interest. 4,5 Furthermore, dissolution-DNP (D-DNP) 6 is increasingly popular in metabolic in vivo studies and MRI since it enables inter alia the detection of anomalous metabolic behavior in tumors. 7−11 The combination of LLSs with DNP 12 and MRI 13 methods has recently been developed for applications on clinical MRI systems. The prototypical LLS is a "singlet state" of a pair of nuclear spins, which corresponds to a population imbalance 14 between the antisymmetric triplet manifold and the symmetric singlet state. In systems comprising two magnetically inequivalent spins, it is possible to populate LLSs directly by DNP at low spin temperatures. 15 LLSs can also be populated without resorting to DNP in systems with magnetically equivalent spins, as in the two-spin system of para-hydrogen 16 and in three-spin systems of methyl groups, 14,17−20 where manifolds of symmetry A and E correspond to irreducible representations of the C 3 group. In both cases, it is possible to induce a long-lived imbalance between states belonging to manifolds with different symmetries at moderately low temperature, provided the rotational energy gap is much larger than the Zeeman splitting. In para-hydrogen, the energy difference between the three triplet states and the singlet state S 0 is ΔE/k B ∼ 170 K in the absence of a magnetic field, while in the methyl group of γ-picoline, 14 the difference between the A and E manifolds is only ΔE/k B ∼ 6 K because of tunneling effects. In this Article, we show that, in an A 2 system with two magnetically equivalent spins, where the Zeeman energy difference between the triplet states T +1 and T −1 and the singlet state S 0 is ΔE/k B ∼ 14 mK at B 0 = 6.7 T, it is possible to use D-DNP to induce a triplet− singlet imbalance (henceforth called TSI in analogy to the A/E imbalance, or AEI, in methyl groups 14 ), which may be written aswhere |S 0 ⟩⟨S 0 | is the population of the singlet state S 0 and | ⟩⟨ | T T represents the...

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Recycling and Imaging of Nuclear Singlet Hyperpolarization

Cited by 100 publications

References 34 publications

Singlet NMR methodology in two-spin-1/2 systems

Singlet NMR methodology in two-spin-1/2 systems

Long-lived nuclear spin states in rapidly rotating CH 2 D groups

Hyperpolarized para-Ethanol

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