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Genetic algorithm‐based optimization of pulse sequences.

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Title: Genetic algorithm‐based optimization of pulse sequences.
Authors: Somai, Vencel1,2 (AUTHOR) Vencel.Somai@cruk.cam.ac.uk, Kreis, Felix3 (AUTHOR), Gaunt, Adam1 (AUTHOR), Tsyben, Anastasia1 (AUTHOR), Chia, Ming Li1 (AUTHOR), Hesse, Friederike1 (AUTHOR), Wright, Alan J.1 (AUTHOR), Brindle, Kevin M.1,4 (AUTHOR)
Source: Magnetic Resonance in Medicine. May2022, Vol. 87 Issue 5, p2130-2144. 15p.
Subjects: Spin excitations, Cost functions, Magnetic fields, Protons, Uniformity
Abstract: Purpose: The performance of pulse sequences in vivo can be limited by fast relaxation rates, magnetic field inhomogeneity, and nonuniform spin excitation. We describe here a method for pulse sequence optimization that uses a stochastic numerical solver that in principle is capable of finding a global optimum. The method provides a simple framework for incorporating any constraint and implementing arbitrarily complex cost functions. Efficient methods for simulating spin dynamics and incorporating frequency selectivity are also described. Methods: Optimized pulse sequences for polarization transfer between protons and X‐nuclei and excitation pulses that eliminate J‐coupling modulation were evaluated experimentally using a surface coil on phantoms, and also the detection of hyperpolarized [2‐13C]lactate in vivo in the case of J‐coupling modulation‐free excitation. Results: The optimized polarization transfer pulses improved the SNR by ~50% with a more than twofold reduction in the B1 field, and J‐coupling modulation‐free excitation was achieved with a more than threefold reduction in pulse length. Conclusion: This process could be used to optimize any pulse when there is a need to improve the uniformity and frequency selectivity of excitation as well as to design new pulses to steer the spin system to any desired achievable state. [ABSTRACT FROM AUTHOR]
Copyright of Magnetic Resonance in Medicine is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: Genetic algorithm‐based optimization of pulse sequences.
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  Data: <searchLink fieldCode="AR" term="%22Somai%2C+Vencel%22">Somai, Vencel</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> Vencel.Somai@cruk.cam.ac.uk</i><br /><searchLink fieldCode="AR" term="%22Kreis%2C+Felix%22">Kreis, Felix</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Gaunt%2C+Adam%22">Gaunt, Adam</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Tsyben%2C+Anastasia%22">Tsyben, Anastasia</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Chia%2C+Ming+Li%22">Chia, Ming Li</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Hesse%2C+Friederike%22">Hesse, Friederike</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wright%2C+Alan+J%2E%22">Wright, Alan J.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Brindle%2C+Kevin+M%2E%22">Brindle, Kevin M.</searchLink><relatesTo>1,4</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Magnetic+Resonance+in+Medicine%22">Magnetic Resonance in Medicine</searchLink>. May2022, Vol. 87 Issue 5, p2130-2144. 15p.
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  Data: <searchLink fieldCode="DE" term="%22Spin+excitations%22">Spin excitations</searchLink><br /><searchLink fieldCode="DE" term="%22Cost+functions%22">Cost functions</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+fields%22">Magnetic fields</searchLink><br /><searchLink fieldCode="DE" term="%22Protons%22">Protons</searchLink><br /><searchLink fieldCode="DE" term="%22Uniformity%22">Uniformity</searchLink>
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  Data: Purpose: The performance of pulse sequences in vivo can be limited by fast relaxation rates, magnetic field inhomogeneity, and nonuniform spin excitation. We describe here a method for pulse sequence optimization that uses a stochastic numerical solver that in principle is capable of finding a global optimum. The method provides a simple framework for incorporating any constraint and implementing arbitrarily complex cost functions. Efficient methods for simulating spin dynamics and incorporating frequency selectivity are also described. Methods: Optimized pulse sequences for polarization transfer between protons and X‐nuclei and excitation pulses that eliminate J‐coupling modulation were evaluated experimentally using a surface coil on phantoms, and also the detection of hyperpolarized [2‐13C]lactate in vivo in the case of J‐coupling modulation‐free excitation. Results: The optimized polarization transfer pulses improved the SNR by ~50% with a more than twofold reduction in the B1 field, and J‐coupling modulation‐free excitation was achieved with a more than threefold reduction in pulse length. Conclusion: This process could be used to optimize any pulse when there is a need to improve the uniformity and frequency selectivity of excitation as well as to design new pulses to steer the spin system to any desired achievable state. [ABSTRACT FROM AUTHOR]
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  Data: <i>Copyright of Magnetic Resonance in Medicine is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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        Value: 10.1002/mrm.29110
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        Type: general
      – SubjectFull: Cost functions
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      – SubjectFull: Magnetic fields
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      – SubjectFull: Uniformity
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      – TitleFull: Genetic algorithm‐based optimization of pulse sequences.
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              Text: May2022
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