Pure Phase Encode Magnetic Resonance Imaging of Fluids in Porous Media

Muir, Colleen E.; Balcom, Bruce J.

doi:10.1016/b978-0-12-397020-6.00002-7

Cited by 34 publications

(24 citation statements)

References 28 publications

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“…Magnetic susceptibility artefacts increase as B 0 increases, but can be reduced by increasing the strength of the spatial‐encoding gradient or by employing phase rather than frequency encoding methods. Thus, if metals of high susceptibility are to be imaged, pure phase encoding methods, such as single‐point imaging,10 can be employed, which are capable of imaging systems with short (≥20 μs) T 2 relaxation times. However, these techniques have other drawbacks, including typically longer experiment times.…”

Section: Imaging Artefactsmentioning

confidence: 99%

Magnetic Resonance Imaging of Electrochemical Cells Containing Bulk Metal

Britton

2014

ChemPhysChem

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The development of improved energy-storage devices, as well as corrosion prevention and metal-electrofinishing technologies, requires knowledge of local composition and transport behaviour in electrolytes near bulk metals, in situ and in real time. It remains a challenge to acquire such data and new analytical methods are required. Recent work shows that magnetic resonance imaging (MRI) is able to map concentration gradients and visualise electrochemical processes in electrochemical cells containing bulk metals. This recent work, along with the challenges, and solutions, associated with MRI of these electrochemical cells are reviewed.

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Section: Imaging Artefactsmentioning

confidence: 99%

Magnetic Resonance Imaging of Electrochemical Cells Containing Bulk Metal

Britton

2014

ChemPhysChem

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“…In considering the effect of RF excitation during spatial encoding gradients in an SPI/SPRITE experiment, we had previously stated that the RF pulse bandwidth was required to be greater than the maximum spread of frequencies in the presence of the strongest phase encode gradient . This is a safe criteria and ensuring this criteria is met, with a short duration RF excitation pulse, ensures minimal phase evolution and an ideal image FOV.…”

Section: Discussionmentioning

confidence: 99%

“…This process is repeated for different magnetic field gradient amplitudes. The SPRITE (Single Point Ramped Imaging with T 1 Enhancement) technique, developed by Balcom et al is an SPI method that employs a series of ramped or stepped gradient values. In this work, SPI measurements were taken with gradient values evenly spaced about zero as in the SPRITE method.…”

Section: Theorymentioning

confidence: 99%

“…Single Point Imaging (SPI) is a magnetic resonance imaging technique that has been successfully employed for many years in the study of systems with short transverse relaxation times. SPI methods allow images to be obtained that are free from distortions introduced by inhomogeneity in the static magnetic field B 0 , magnetic susceptibility mismatch and chemical shift . SPI involves the application of radio‐frequency excitation pulses in the presence of a magnetic field gradient.…”

Section: Introductionmentioning

confidence: 99%

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Systematic image alteration due to phase accumulation during RF pulse excitation in pure phase encode magnetic resonance imaging

McDonald

MacMillan

Newling

et al. 2016

Concepts Magnetic Resonance

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The SPI/SPRITE class of techniques in magnetic resonance imaging are pure phase encode methods that are well established for systems with short transverse signal lifetimes. Applying a broadband radio-frequency pulse in the presence of a magnetic field gradient is unconventional in MRI but fundamental to these methods. Ordinarily, it is assumed that the excitation is instantaneous and any possible phase evolution during the RF pulse is ignored. High quality, quantitative imaging of a variety of samples over many years suggests that the off-resonance effects of the RF pulse, with consequent phase accumulation during the pulse, are not significant. However, a reconsideration of the RF pulse behavior in related work has shown that phase accumulation during the pulse may be non-negligible in some circumstances.The effect of phase accumulation during the RF pulse is investigated through simulation of one-dimensional SPI experiments and is shown to manifest as a systematic scaling of the image field-of-view (FOV). The FOV scaling effect is also verified experimentally. One-dimensional profiles of a cylindrical elastomer sample were acquired employing a 2.4 T horizontal bore magnet. Experiments were undertaken with variation of the experimental RF pulse duration. Under typical experimental parameters, neglecting the phase accumulation during the RF pulse is acceptable.

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“…MR/MRI techniques, in principle, can directly quantify the residual water saturation, discriminate the residual water from pore gas, and characterize pore level behavior in situ, but this has not been yet demonstrated. High field MRI instruments have been previously employed for hydrate studies, but low field instruments are advantageous since they minimize susceptibility effects [4]. At low static fields, appropriate MRI methods can spatially and temporally quantify residual fluids [5] (water and gas) and reveal the growth pattern of gas hydrate.…”

Section: Introductionmentioning

confidence: 99%

Monitoring gas hydrate formation with magnetic resonance imaging in a metallic core holder

et al. 2019

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Methane hydrate deposits world-wide are promising sources of natural gas. Magnetic Resonance Imaging (MRI) has proven useful in previous studies of hydrate formation. In the present work, methane hydrate formation in a water saturated sand pack was investigated employing an MRI-compatible metallic core holder at low magnetic ﬁeld with a suite of advanced MRI methods developed at the UNB MRI Centre. The new MRI methods are intended to permit observation and quantiﬁcation of residual ﬂuids in the pore space as hydrate forms. Hydrate formation occurred in the water-saturated sand at 1500 psi and 4 °C. The core holder has a maximum working pressure of 4000 psi between -28 and 80 °C. The heat-exchange jacket enclosing the core holder enabled very precise control of the sample temperature. A pure phase encode MRI technique, SPRITE, and a bulk T1-T2 MR method provided high quality measurements of pore ﬂuid saturation. Rapid 1D SPRITE MRI measurements time resolved the disappearance of pore water and hence the growth of hydrate in the sand pack. 3D π-EPI images conﬁrmed that the residual water was inhomogeneously distributed along the sand pack. Bulk T1-T2 measurements discriminated residual water from the pore gas during the hydrate formation. A recently published local T1-T2 method helped discriminate bulk gas from the residual ﬂuids in the sample. Hydrate formation commenced within two hours of gas supply. Hydrate formed throughout the sand pack, but maximum hydrate was observed at the interface between the gas pressure head and the sand pack. This irregular pattern of hydrate formation became more uniform over 24 hours. The rate of hydrate formation was greatest in the ﬁrst two hours of reaction. An SE-SPI T2 map showed the T2 distribution changed considerably in space and time as hydrate formation continued. Changes in the T2 distribution are interpreted as pore level changes in residual water content and environment.

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Pure Phase Encode Magnetic Resonance Imaging of Fluids in Porous Media

Cited by 34 publications

References 28 publications

Magnetic Resonance Imaging of Electrochemical Cells Containing Bulk Metal

Magnetic Resonance Imaging of Electrochemical Cells Containing Bulk Metal

Systematic image alteration due to phase accumulation during RF pulse excitation in pure phase encode magnetic resonance imaging

Monitoring gas hydrate formation with magnetic resonance imaging in a metallic core holder

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