Imaging the Long-Range Dipolar Field in Structured Liquid State Samples

Bowtell, Richard; Gutteridge, S.; Ramanathan, Chandrasekhar

doi:10.1006/jmre.2001.2323

Cited by 50 publications

(60 citation statements)

References 17 publications

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“…If θ = π, the magnetization after the rf pulse reduces to (8) Equations (6a) and (6b) can be combined into two second order linear differential equations in , which can be solved with diagonalization transformation. With the initial values of the magnetization just before the rf pulse taken as and , the zeroth order transverse magnetization becomes (9) The zeroth order longitudinal magnetization can be found by solving (6b) with the substitution of (9): (10) The coefficients in (9) and (10) are…”

Section: Magnetization During a Finite Rf Pulsementioning

confidence: 99%

“…1. The signal produced by the sequence exhibits interesting relaxation, diffusion, and structural properties [7][8][9][10][11][12][13][14][15][16][17], and provides contrast for magnetic resonance imaging (MRI) that is fundamentally different from that by conventional techniques [18][19][20][21][22][23][24]. Nevertheless applications of such signal have been severely limited by its small amplitude in most tissues primarily due to transverse relaxation, despite the fact that some improvement can be obtained, for example, with simultaneous acquisition of multiple orders of quantum coherence [25,26].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical studies of the effect of the dipolar field in multiple spin-echo sequences with refocusing pulses of finite duration

Wong

Kennedy

Kwok

et al. 2007

Journal of Magnetic Resonance

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It has been observed recently that the finite duration of refocusing rf pulses in a multiecho acquisition of the signal formed under the influence of dipolar field leads to significant signal attenuation [S. Kennedy et al., Proc. Intl. Soc. Mag. Reson. Med. 13, 2288(2005]. Hereto we quantify the phenomenon by evaluating analytically the influences of both the distant dipolar field (DDF) and transverse relaxation T 2 on the magnetization in a multiecho pulse sequence based on Correlation Spectroscopy Revamped by Asymmetric z-gradient Echo Detection (CRAZED). Analytic expressions for the magnetization were obtained, which demonstrate explicitly the origin of rephased signal in the presence of the finite π pulses in the multiecho train. The expressions also explain the effects of DDF and T 2 during the refocusing pulses on the signal strength, and show the substantial signal dependence on the phase of the rf pulses. We show that when the DDF effect during the pulse is canceled, the signal rises primarily during the free evolution time in the acquisition period. This elucidates the signal attenuation when the rf pulses expand a significant proportion of time in the sequence. In addition, we performed an optimization on the number of refocusing pulses that maximizes the total acquired signal using parameters for water, brain white matter and muscle. We found that maximal signal-to-noise ratio is obtained when the pulse duration approximately equals the free evolution time in the samples with a wide range of T 2 .

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Section: Magnetization During a Finite Rf Pulsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical studies of the effect of the dipolar field in multiple spin-echo sequences with refocusing pulses of finite duration

Wong

Kennedy

Kwok

et al. 2007

Journal of Magnetic Resonance

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“…For example, imaging sequences utilizing DDF have been devised to provide new contrast in magnetic resonance imaging applications, 7,8 to reduce linewidths in magnetic resonance spectroscopy experiments in the presence of large magnetic field inhomogeneities, [9][10][11] for functional MRI studies, 12,13 for brown adipose tissue detection, [14][15][16] and to measure temperature in vivo with high accuracy. 17,18 The main feature of DDF-based sequences is that the DDFderived signal comes primarily from pairs of nuclear spins that are separated by a "correlation distance," a user-controllable distance that can be tuned from a few micrometers to several millimeters, allowing sample structures to be probed at a microscopic scale without the loss of sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Remote detection of hyperpolarized 129Xe resonances via multiple distant dipolar field interactions with 1H

Zhang

Antonacci

Burant

et al. 2016

The Journal of Chemical Physics

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A remote detection scheme utilizing the distant dipolar field interaction between two different spin species was proposed by Granwehr et al. [J. Magn. Reson. 176(2), 125 (2005)]. In that sequence 1 H spins were detected indirectly via their dipolar field interaction with 129 Xe spins, which served as the sensing spins. Here we propose a modification of the proposed detection scheme that takes advantage of the longer T 1 relaxation time of xenon to create a long lasting dipolar field with which the fast relaxing 1 H spins are allowed to interact many times during a single acquisition. This new acquisition scheme improves detection sensitivity, but it also presents some challenges. Published by AIP Publishing. [http://dx

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“…Some of the experiments are discussed in a non-remote detection modality in Refs. [317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335]. Another situation that might commonly arise in remote detection experiments is when some of the carrier nucleus is bound and some is mobile, e.g., xenon in solution with some sample of interest versus free xenon gas.…”

Section: Indirect Detection With the Distant Dipolar Fieldmentioning

confidence: 99%

“…The long-range nature of iMQCs and DDF effects have made them useful probes of mesoscopic structure: e.g., as a contrast mechanism in magnetic resonance imaging [317,318,319,320,321,322,323,324,325]; in NMR multipleecho, scattering, and microscopy-type experiments [326,327,328,329,330,331,332,333]; and even in the direct mapping of the dipolar field or magnetization distribution in solution [334,335]. Some of these experiments rely on the facts that the dipolar field is active only…”

Section: Densitymentioning

confidence: 99%

Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

Urban

2004

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Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantummechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics.The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nu-2 clei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy.The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.

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Imaging the Long-Range Dipolar Field in Structured Liquid State Samples

Cited by 50 publications

References 17 publications

Theoretical studies of the effect of the dipolar field in multiple spin-echo sequences with refocusing pulses of finite duration

Theoretical studies of the effect of the dipolar field in multiple spin-echo sequences with refocusing pulses of finite duration

Remote detection of hyperpolarized 129Xe resonances via multiple distant dipolar field interactions with 1H

Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

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