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Extended phase graph formalism for systems with magnetization transfer and exchange

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Extended phase graph formalism for systems with magnetization transfer and exchange. / Malik, Shaihan J.; Teixeira, Rui Pedro A.G.; Hajnal, Joseph V.

In: Magnetic Resonance in Medicine, Vol. 80, No. 2, 15.12.2017, p. 767-779.

Research output: Contribution to journalArticle

Harvard

Malik, SJ, Teixeira, RPAG & Hajnal, JV 2017, 'Extended phase graph formalism for systems with magnetization transfer and exchange', Magnetic Resonance in Medicine, vol. 80, no. 2, pp. 767-779. https://doi.org/10.1002/mrm.27040

APA

Malik, S. J., Teixeira, R. P. A. G., & Hajnal, J. V. (2017). Extended phase graph formalism for systems with magnetization transfer and exchange. Magnetic Resonance in Medicine, 80(2), 767-779. https://doi.org/10.1002/mrm.27040

Vancouver

Malik SJ, Teixeira RPAG, Hajnal JV. Extended phase graph formalism for systems with magnetization transfer and exchange. Magnetic Resonance in Medicine. 2017 Dec 15;80(2):767-779. https://doi.org/10.1002/mrm.27040

Author

Malik, Shaihan J. ; Teixeira, Rui Pedro A.G. ; Hajnal, Joseph V. / Extended phase graph formalism for systems with magnetization transfer and exchange. In: Magnetic Resonance in Medicine. 2017 ; Vol. 80, No. 2. pp. 767-779.

Bibtex Download

@article{f84da893ccc54cdebcffdeb05cb6dafe,
title = "Extended phase graph formalism for systems with magnetization transfer and exchange",
abstract = "Purpose: An extended phase graph framework (EPG-X) for modeling systems with exchange or magnetization transfer (MT) is proposed. Theory: EPG-X models coupled two-compartment systems by describing each compartment with separate phase graphs that exchange during evolution periods. There are two variants: EPG-X(BM) for systems governed by the Bloch-McConnell equations, and EPG-X(MT) for the pulsed MT formalism. For the MT case, the {"}bound{"} protons have no transverse components, so their phase graph consists of only longitudinal states. Methods: The EPG-X model was validated against steady-state solutions and isochromat-based simulation of gradient-echo sequences. Three additional test cases were investigated: (i) MT effects in multislice turbo spin-echo; (ii) variable flip angle gradient-echo imaging of the type used for MR fingerprinting; and (iii) water exchange in multi-echo spin-echo T2 relaxometry. Results: EPG-X was validated successfully against isochromat based transient simulations and known steady-state solutions. EPG-X(MT) simulations matched in-vivo measurements of signal attenuation in white matter in multislice turbo spin-echo images. Magnetic resonance fingerprinting-style experiments with a bovine serum albumin (MT) phantom showed that the data were not consistent with a single-pool model, but EPG-X(MT) could be used to fit the data well. The EPG-X(BM) simulations of multi-echo spin-echo T2 relaxometry suggest that exchange could lead to an underestimation of the myelin-water fraction. Conclusions: The EPG-X framework can be used for modeling both steady-state and transient signal response of systems exhibiting exchange or MT. This may be particularly beneficial for relaxometry approaches that rely on characterizing transient rather than steady-state sequences.",
keywords = "Bloch-McConnell equations, Exchange, Extended phase graphs, Magnetization transfer, Relaxometry, Sequence simulation",
author = "Malik, {Shaihan J.} and Teixeira, {Rui Pedro A.G.} and Hajnal, {Joseph V.}",
year = "2017",
month = "12",
day = "15",
doi = "10.1002/mrm.27040",
language = "English",
volume = "80",
pages = "767--779",
journal = "Magnetic resonance in medicine",
issn = "0740-3194",
number = "2",

}

RIS (suitable for import to EndNote) Download

TY - JOUR

T1 - Extended phase graph formalism for systems with magnetization transfer and exchange

AU - Malik, Shaihan J.

AU - Teixeira, Rui Pedro A.G.

AU - Hajnal, Joseph V.

PY - 2017/12/15

Y1 - 2017/12/15

N2 - Purpose: An extended phase graph framework (EPG-X) for modeling systems with exchange or magnetization transfer (MT) is proposed. Theory: EPG-X models coupled two-compartment systems by describing each compartment with separate phase graphs that exchange during evolution periods. There are two variants: EPG-X(BM) for systems governed by the Bloch-McConnell equations, and EPG-X(MT) for the pulsed MT formalism. For the MT case, the "bound" protons have no transverse components, so their phase graph consists of only longitudinal states. Methods: The EPG-X model was validated against steady-state solutions and isochromat-based simulation of gradient-echo sequences. Three additional test cases were investigated: (i) MT effects in multislice turbo spin-echo; (ii) variable flip angle gradient-echo imaging of the type used for MR fingerprinting; and (iii) water exchange in multi-echo spin-echo T2 relaxometry. Results: EPG-X was validated successfully against isochromat based transient simulations and known steady-state solutions. EPG-X(MT) simulations matched in-vivo measurements of signal attenuation in white matter in multislice turbo spin-echo images. Magnetic resonance fingerprinting-style experiments with a bovine serum albumin (MT) phantom showed that the data were not consistent with a single-pool model, but EPG-X(MT) could be used to fit the data well. The EPG-X(BM) simulations of multi-echo spin-echo T2 relaxometry suggest that exchange could lead to an underestimation of the myelin-water fraction. Conclusions: The EPG-X framework can be used for modeling both steady-state and transient signal response of systems exhibiting exchange or MT. This may be particularly beneficial for relaxometry approaches that rely on characterizing transient rather than steady-state sequences.

AB - Purpose: An extended phase graph framework (EPG-X) for modeling systems with exchange or magnetization transfer (MT) is proposed. Theory: EPG-X models coupled two-compartment systems by describing each compartment with separate phase graphs that exchange during evolution periods. There are two variants: EPG-X(BM) for systems governed by the Bloch-McConnell equations, and EPG-X(MT) for the pulsed MT formalism. For the MT case, the "bound" protons have no transverse components, so their phase graph consists of only longitudinal states. Methods: The EPG-X model was validated against steady-state solutions and isochromat-based simulation of gradient-echo sequences. Three additional test cases were investigated: (i) MT effects in multislice turbo spin-echo; (ii) variable flip angle gradient-echo imaging of the type used for MR fingerprinting; and (iii) water exchange in multi-echo spin-echo T2 relaxometry. Results: EPG-X was validated successfully against isochromat based transient simulations and known steady-state solutions. EPG-X(MT) simulations matched in-vivo measurements of signal attenuation in white matter in multislice turbo spin-echo images. Magnetic resonance fingerprinting-style experiments with a bovine serum albumin (MT) phantom showed that the data were not consistent with a single-pool model, but EPG-X(MT) could be used to fit the data well. The EPG-X(BM) simulations of multi-echo spin-echo T2 relaxometry suggest that exchange could lead to an underestimation of the myelin-water fraction. Conclusions: The EPG-X framework can be used for modeling both steady-state and transient signal response of systems exhibiting exchange or MT. This may be particularly beneficial for relaxometry approaches that rely on characterizing transient rather than steady-state sequences.

KW - Bloch-McConnell equations

KW - Exchange

KW - Extended phase graphs

KW - Magnetization transfer

KW - Relaxometry

KW - Sequence simulation

UR - https://github.com/mriphysics/EPG-X

UR - http://www.scopus.com/inward/record.url?scp=85041125821&partnerID=8YFLogxK

U2 - 10.1002/mrm.27040

DO - 10.1002/mrm.27040

M3 - Article

AN - SCOPUS:85041125821

VL - 80

SP - 767

EP - 779

JO - Magnetic resonance in medicine

JF - Magnetic resonance in medicine

SN - 0740-3194

IS - 2

ER -

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