The dependence on magnetic field strength of correlated internal gradient relaxation time distributions in heterogeneous materials

Washburn, Kathryn E.; Eccles, C.D.; Callaghan, Paul T.

doi:10.1016/j.jmr.2008.05.025

Cited by 70 publications

(31 citation statements)

References 31 publications

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“…At the highest frequency (corresponding to the highest magnetic field strength) the T 2 measurement is influenced strongly by diffusion in internal magnetic field gradients induced by the susceptibility difference at the rock/water interface [48][49][50]. These internal gradients have been shown to scale with magnetic field strength [51]. We will consider the influence of magnetic field strength on T 2 measurements in more detail in a future publication.…”

Section: Surface Interactionsmentioning

confidence: 99%

A rapid measurement of : The DECPMG sequence

Mitchell

Hürlimann

Fordham

2009

Journal of Magnetic Resonance

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Section: Surface Interactionsmentioning

confidence: 99%

A rapid measurement of : The DECPMG sequence

Mitchell

Hürlimann

Fordham

2009

Journal of Magnetic Resonance

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“…In particular, analyses of factors that result in signal deviation from the ideal SPGR and bSSFP models are needed. These factors include diffusion [20, 21], magnetization transfer [22], signal modeling [23], magnetization spoiling [24, 25], magic angle effects [26], internal gradients [27, 28] and noise distribution [29, 30]. Nevertheless, the present work stands to indicate the feasibility of high quality in-vivo HR mapping of PgWF in articular cartilage of the human knee joint in an acceptable clinical acquisition time through use of BMC-mcDESPOT.…”

Section: Discussionmentioning

confidence: 99%

Clinical high-resolution mapping of the proteoglycan-bound water fraction in articular cartilage of the human knee joint

Bouhrara

Reiter

Sexton

et al. 2017

Magnetic Resonance Imaging

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Purpose we applied a recently introduced method to achieve clinically-feasible in-vivo mapping of the proteoglycan water fraction (PgWF) of human knee cartilage with improved spatial resolution and stability as compared to existing methods. Material and Methods Multicomponent driven equilibrium single-pulse observation of T1 and T2 (mcDESPOT) datasets were acquired from the knees of two healthy young subjects and one older subject with previous knee injury. Each dataset was processed using Bayesian Monte Carlo (BMC) analysis incorporating a two-component tissue model. We assessed the performance and reproducibility of BMC and of the conventional analysis of stochastic region contraction (SRC) in the estimation of PgWF. Stability of the BMC analysis of PgWF was tested in two independent high-resolution (HR) datasets from each of the two young subjects. Results Unlike SRC, the BMC-derived maps from the two HR datasets were essentially identical. Furthermore, SRC maps showed substantial random variation in estimated PgWF, and mean values that differed from those obtained using BMC. In addition, PgWF maps derived from conventional low-resolution (LR) datasets exhibited partial volume and magnetic susceptibility effects. These artifacts were absent in HR PgWF images. Finally, our analysis showed regional variation in PgWF estimates, and substantially higher values in the younger subjects as compared to the older subject. Conclusions BMC-mcDESPOT permits HR in-vivo mapping of PgWF in human knee cartilage in a clinically-feasible acquisition time. HR mapping reduces the impact of partial volume and magnetic susceptibility artifacts compared to LR mapping. Finally, BMC-mcDESPOT demonstrated excellent reproducibility in the determination of PgWF.

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“…B 0 . 1 T) where the inhomogeneous distribution of susceptibility induced internal gradients scale with field strength (30). At low magnetic fields (B 0 , 1 T) these internal gradients can be less detrimental for favorable samples and so the complexity of the APGSTE sequence is not required.…”

Section: Figurementioning

confidence: 99%

Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

Mitchell

Johns

2009

Concepts Magnetic Resonance

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Pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) is one of the few experimental techniques that can determine directly mean square molecular displacements, allowing self-diffusion coefficient of liquids to be derived. PFG measurements are used commonly for diffusion, flow, and microstructure characterization. However, these conventional PFG experiments are often time consuming, requiring the gradient strength or observation time to be incremented independently. Here we discuss how the rapid Difftrain pulse sequence has proved invaluable in the study of time sensitive systems by allowing multiple observation times to be probed in a single scan. Difftrain has been applied successfully to the study of emulsions, surfactant solutions, bead packs, and permeable rock cores. We discuss various implementations of the Difftrain pulse sequence, suggest suitable phase cycles, and review the applications to date.

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The dependence on magnetic field strength of correlated internal gradient relaxation time distributions in heterogeneous materials

Cited by 70 publications

References 31 publications

A rapid measurement of : The DECPMG sequence

A rapid measurement of : The DECPMG sequence

Clinical high-resolution mapping of the proteoglycan-bound water fraction in articular cartilage of the human knee joint

Rapid measurements of diffusion using PFG: Developments and applications of the Difftrain pulse sequence

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