Reducing the duration of broadband excitation pulses using optimal control with limited RF amplitude

Thomas E. Skinner; Timo O. Reiss; Burkhard Luy; Navin Khaneja; Steffen J. Glaser

doi:10.1016/j.jmr.2003.12.001

Reducing the duration of broadband excitation pulses using optimal control with limited RF amplitude

Thomas E. Skinner, Timo O. Reiss, Burkhard Luy, Navin Khaneja, Steffen J. Glaser

Associate Professorship of Organic Chemistry

Research output: Contribution to journal › Article › peer-review

119 Scopus citations

Abstract

Combining optimal control theory with a new RF limiting step produces pulses with significantly reduced duration and improved performance for a given maximum RF amplitude compared to previous broadband excitation by optimized pulses (BEBOP). The resulting pulses tolerate variations in RF homogeneity relevant for standard high-resolution NMR probes. Design criteria were transformation of I_z→I_x over resonance offsets of ±20kHz and RF variability of ±5%, with a pulse length of 500μs and peak RF amplitude equal to 17.5kHz. Simulations transform I_z to greater than 0.995 I_x, with phase deviations of the final magnetization less than 2°, over ranges of resonance offset and RF variability that exceed the design targets. Experimental performance of the pulse is in excellent agreement with the simulations. Performance tradeoffs for yet shorter pulses or pulses with decreased digitization are also investigated.

Original language	English
Pages (from-to)	68-74
Number of pages	7
Journal	Journal of Magnetic Resonance
Volume	167
Issue number	1
DOIs	https://doi.org/10.1016/j.jmr.2003.12.001
State	Published - Mar 2004

Keywords

BEBOP
Broadband excitation
Optimal control theory

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10.1016/j.jmr.2003.12.001

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title = "Reducing the duration of broadband excitation pulses using optimal control with limited RF amplitude",

abstract = "Combining optimal control theory with a new RF limiting step produces pulses with significantly reduced duration and improved performance for a given maximum RF amplitude compared to previous broadband excitation by optimized pulses (BEBOP). The resulting pulses tolerate variations in RF homogeneity relevant for standard high-resolution NMR probes. Design criteria were transformation of Iz→Ix over resonance offsets of ±20kHz and RF variability of ±5%, with a pulse length of 500μs and peak RF amplitude equal to 17.5kHz. Simulations transform Iz to greater than 0.995 Ix, with phase deviations of the final magnetization less than 2°, over ranges of resonance offset and RF variability that exceed the design targets. Experimental performance of the pulse is in excellent agreement with the simulations. Performance tradeoffs for yet shorter pulses or pulses with decreased digitization are also investigated.",

keywords = "BEBOP, Broadband excitation, Optimal control theory",

author = "Skinner, {Thomas E.} and Reiss, {Timo O.} and Burkhard Luy and Navin Khaneja and Glaser, {Steffen J.}",

note = "Funding Information: B.L. thanks the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft (Emmy Noether fellowship LU 835/1-1) for support. S.J.G. acknowledges support from the Deutsche Forschungsgemeinschaft for Grants Gl 203/3-1 and Gl 203/4-1 and the Fonds der Chemischen Industrie. N.K. would like to acknowledge Darpa Grant F49620-0101-00556.",

year = "2004",

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doi = "10.1016/j.jmr.2003.12.001",

language = "English",

volume = "167",

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AU - Skinner, Thomas E.

AU - Reiss, Timo O.

AU - Luy, Burkhard

AU - Khaneja, Navin

AU - Glaser, Steffen J.

N1 - Funding Information: B.L. thanks the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft (Emmy Noether fellowship LU 835/1-1) for support. S.J.G. acknowledges support from the Deutsche Forschungsgemeinschaft for Grants Gl 203/3-1 and Gl 203/4-1 and the Fonds der Chemischen Industrie. N.K. would like to acknowledge Darpa Grant F49620-0101-00556.

PY - 2004/3

Y1 - 2004/3

N2 - Combining optimal control theory with a new RF limiting step produces pulses with significantly reduced duration and improved performance for a given maximum RF amplitude compared to previous broadband excitation by optimized pulses (BEBOP). The resulting pulses tolerate variations in RF homogeneity relevant for standard high-resolution NMR probes. Design criteria were transformation of Iz→Ix over resonance offsets of ±20kHz and RF variability of ±5%, with a pulse length of 500μs and peak RF amplitude equal to 17.5kHz. Simulations transform Iz to greater than 0.995 Ix, with phase deviations of the final magnetization less than 2°, over ranges of resonance offset and RF variability that exceed the design targets. Experimental performance of the pulse is in excellent agreement with the simulations. Performance tradeoffs for yet shorter pulses or pulses with decreased digitization are also investigated.

AB - Combining optimal control theory with a new RF limiting step produces pulses with significantly reduced duration and improved performance for a given maximum RF amplitude compared to previous broadband excitation by optimized pulses (BEBOP). The resulting pulses tolerate variations in RF homogeneity relevant for standard high-resolution NMR probes. Design criteria were transformation of Iz→Ix over resonance offsets of ±20kHz and RF variability of ±5%, with a pulse length of 500μs and peak RF amplitude equal to 17.5kHz. Simulations transform Iz to greater than 0.995 Ix, with phase deviations of the final magnetization less than 2°, over ranges of resonance offset and RF variability that exceed the design targets. Experimental performance of the pulse is in excellent agreement with the simulations. Performance tradeoffs for yet shorter pulses or pulses with decreased digitization are also investigated.

KW - BEBOP

KW - Broadband excitation

KW - Optimal control theory

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SP - 68

EP - 74

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

IS - 1

ER -

Reducing the duration of broadband excitation pulses using optimal control with limited RF amplitude

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Keywords

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