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Magnetic Resonance RF Pulse Design by Optimal Control With Physical Constraints
2018
IEEE Transactions on Medical Imaging
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Optimal control approaches have proved useful in designing RF pulses for large tip-angle applications. ...
A typical challenge for optimal control design is the inclusion of constraints resulting from physiological or technical limitations, that assure the realizability of the optimized pulses. ...
Acknowledgments This work is partially funded by the Austrian Science Fund (FWF) in the context of project "SFB F -" (Mathematical Optimization and Applications in Biomedical Sciences). ...
doi:10.1109/tmi.2017.2758391
pmid:28981407
fatcat:vri5pffcjne6hgufwmwikw77x4
Quick Reduction of Specific Absorption Rate Constraints in Parallel RF Excitation Pulse Design by Maximum Volume Inscribed Ellipsoids
2019
Concepts in magnetic resonance. Part A, Bridging education and research
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In medical magnetic resonance imaging, parallel radio frequency excitation pulses have to respect a large number of specific absorption rate constraints. ...
We propose to replace a collection of such constraints by the single constraint which corresponds to the associated maximum volume inscribed ellipsoid and implies all original constraints. ...
The remaining 12 to 36 SAR constraints in the pulse design examples are dealt with by Lagrange multipliers and a conjugate gradient algorithm in a small tip angle 2 Concepts in Magnetic Resonance Part ...
doi:10.1155/2019/7369845
fatcat:ctoje3i4s5ghhbgne3vpg533vu
Clipped DeepControl: deep neural network two-dimensional pulse design with an amplitude constraint layer
[article]
2022
arXiv
pre-print
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Advanced radio-frequency pulse design used in magnetic resonance imaging has recently been demonstrated with deep learning of (convolutional) neural networks and reinforcement learning. ...
conventional optimal control computation. ...
This is in our studies 2D RF pulses computed with optimal control. ...
arXiv:2201.08668v1
fatcat:3mmdrbccfvbi5lwbkkmnqn6nhy
Joint Design of RF and gradient waveforms via auto-differentiation for 3D tailored excitation in MRI
[article]
2021
arXiv
pre-print
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2021 pre-print arXiv:2008.10594v2 fatcat:koejxkuubvcodarxfz7hq7eayuOther Versions
This paper proposes a new method for joint design of radiofrequency (RF) and gradient waveforms in Magnetic Resonance Imaging (MRI), and applies it to the design of 3D spatially tailored saturation and ...
To enforce hardware limits (peak RF, gradient, and slew rate), we use a change of variables that makes the 3D pulse design problem effectively unconstrained; we then optimize the resulting problem directly ...
Our approach may remind readers of optimal control (OC) based pulse design methods [30] , [31] . ...
arXiv:2008.10594v3
fatcat:aqs6l7ljcfdhdjhs6bmqyylwgu
Iterative RF pulse design for multidimensional, small-tip-angle selective excitation
2005
Magnetic Resonance in Medicine
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In this paper, k-space-based design of multidimensional RF pulses is formulated as a quadratic optimization problem, and solved efficiently by the iterative conjugate-gradient (CG) algorithm. ...
In addition, regularization techniques allow control over integrated and peak pulse power. Magn Reson Med 54:908 -917, 2005. ...
In the small-tip-angle regime, one can design an optimal RF pulse by minimizing a cost function that includes an excitation error measure and a pulse energy term that allows for a soft constraint on the ...
doi:10.1002/mrm.20631
pmid:16155881
fatcat:7gz2nlsxunaj5mf3yvyr3ykrom
Tailoring the optimal control cost function to a desired output: application to minimizing phase errors in short broadband excitation pulses
2005
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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NEW ABSTRACT:]] The de facto standard cost function has been used heretofore to characterize the performance of pulses designed using optimal control theory. ...
Compared to previous broadband excitation by optimized pulses (BEBOP), significantly shorter pulses are achievable, with only marginally reduced performance. ...
A 125 µs pulse was designed by changing the cost function used in our previous optimal control procedures [4, 5] . ...
doi:10.1016/j.jmr.2004.09.011
pmid:15589403
fatcat:d4jtm7oea5a2lnya22xifct3y4
Optimal pulse design in quantum control: A unified computational method
2011
Proceedings of the National Academy of Sciences of the United States of America
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We present such robust pulse designs as an optimal control problem of a continuum of bilinear systems with a common control function. ...
Simulation Results A fundamental challenge in pulse design for magnetic resonance applications is to develop robust pulses that compensate for the Larmor dispersion and rf inhomogeneity over the sample ...
We present such robust pulse designs as an optimal control problem of a continuum of bilinear systems with a common control function. ...
doi:10.1073/pnas.1009797108
pmid:21245345
pmcid:PMC3033291
fatcat:25jfwjx44vdr5pklhnqsxocis4
Exploring the limits of broadband excitation and inversion pulses
2004
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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A systematic study of rf-limited BEBOP (Broadband Excitation By Optimized Pulses) and BIBOP (Broadband Inversion By Optimized Pulses) pulses with respect to bandwidth and B1-field is presented. ...
The design of broadband excitation and inversion pulses with compensation of B1-field inhomogeneity is a long standing goal in high resolution NMR spectroscopy. ...
A different optimization procedure that was first used in magnetic resonance for the optimization of band-selective pulses in MRI [21, 22, 23] is based on optimal control theory. ...
doi:10.1016/j.jmr.2004.06.017
pmid:15388086
fatcat:jacpuvosp5hmfidc4v4rd52cdu
Minimum TR radiofrequency-pulse design for rapid gradient echo sequences
2021
Magnetic Resonance in Medicine
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The optimal RF pulse is found by meeting spatial encoding, peripheral nerve stimulation (PNS) and SAR constraints. ...
The TR-optimal framework designs RF pulses for a range of pulse parameters, specifically to minimize sequence TR. ...
the simpler approach of tabulating the relationship between E RF and T pulse for each design scenario by precomputing RF pulse designs for a range of B control 1 from 2 μT to 13 μT (Table 1 ). ...
doi:10.1002/mrm.28705
pmid:33586800
fatcat:gnbllsovjnby5m62ugm7o7lvre
Optimal control design of excitation pulses that accommodate relaxation
2007
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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The utility of designing pulses to produce specific phase in the final magnetization is also presented. ...
An optimal control algorithm for mitigating the effects of T 1 and T 2 relaxation during the application of long pulses is derived. ...
Designing pulses with specific phase characteristics for the final magnetization is a new approach in our optimal control work and also has many potential applications. ...
doi:10.1016/j.jmr.2007.08.007
pmid:17804269
fatcat:tbixnppedrdy3lkwj2yy7rjgm4
RF power design optimization in MRI system
2021
Magnetic Resonance Letters
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Tian-zi, RF power design optimization in MRI system, Magnetic Resonance Letters, https://doi.Abstract: Magnetic resonance image quality and patient safety have been the focus of engineering and research ...
The design of the RF in the MR system is systematically summarized, including the entire transmission chain, sequence algorithm and RF pulse design, and the probabilities for improvement and optimization ...
The hardware requirements can be reduced by optimizing the sequences and RF pulses design to avoid the extremely demanding RF energy. ...
doi:10.1016/j.mrl.2021.100006
fatcat:37pv7wtdnravredlmnfvkjrsw4
Exploring the limits of broadband excitation and inversion: II. Rf-power optimized pulses
2008
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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Reson. 170 (2004) 236-243], optimal control theory was employed in a systematic study to establish physical limits for the minimum rf-amplitudes required in broadband excitation and inversion pulses. ...
The resulting pulses display a variety of pulse shapes with highly modulated rf-amplitudes and generally show better performance than corresponding pulses with identical pulse length and rf-power, but ...
s work was supported by the European integrated programs Bio-DNP and QAP, the DFG (Gl 203/6-1), the SFB 631 and by the Fonds der Chemischen Industrie. ...
doi:10.1016/j.jmr.2008.05.023
pmid:18586540
fatcat:k5l3jzqdlrbvdpzn5rxgla2p54
Application of optimal control to CPMG refocusing pulse design
2010
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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2010 pre-print arXiv:1002.1702v1 fatcat:nhcvpwidpfhkzpwnq2masfrhfiOther Versions
We show that with this refocusing pulse, the CPMG sequence can refocus over 98% of magnetization for resonance offsets up to 3.2 times the maximum RF amplitude, even in the presence of +/- 10% RF inhomogeneity ...
We apply optimal control theory (OCT) to the design of refocusing pulses suitable for the CPMG sequence that are robust over a wide range of B0 and B1 offsets. ...
This work was supported in part by the National Security Agency (NSA) under Army Research Office (ARO) contract number W911NF-05-1-0469. ...
doi:10.1016/j.jmr.2010.09.003
pmid:20933448
fatcat:cb7zyukhyjgpdd7zt67twbkza4
Control of inhomogeneous atomic ensembles of hyperfine qudits
2012
Physical Review A. Atomic, Molecular, and Optical Physics
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Such a capability is essential to the design of robust pulses that mitigate the effects of experimental uncertainty and also for application to tomographic addressing of particular members of an extended ...
We study the ability to control d-dimensional quantum systems (qudits) encoded in the hyperfine spin of alkali-metal atoms through the application of radio- and microwave-frequency magnetic fields in the ...
With this structure, we can achieve control on the system through a simple series of SU (2) rotations driven alternately by resonant rf and microwave fields. ...
doi:10.1103/physreva.85.022302
fatcat:x5gsnia2yfctxffygswbiubc3i
Heteronuclear refocusing by nonlinear phase and amplitude modulation on a single transmitter channel
2014
Journal of magnetic resonance (San Diego, Calif. 1997 : Print)
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Nonlinear phase and amplitude modulated waveforms designed to simultaneously refocus magnetization at 128 kHz ( 13 C) and 510 kHz ( 1 H) were generated numerically with optimal control. ...
For controlling polarizer chemistry, spare TTL channels of portable NMR spectrometers can be used to pulse program reaction timings in synchrony with heteronuclear RF transformations. ...
Acknowledgments We thank Craig Eccles and Andrew Coy for help with implementing phase and amplitude modulation on the Magritek KEA. ...
doi:10.1016/j.jmr.2014.05.010
pmid:24954513
pmcid:PMC4206526
fatcat:4jgphjcdjbe5pi5f7qsfdrle6y
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