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- Title
Genetic algorithm‐based optimization of pulse sequences.
- Authors
Somai, Vencel; Kreis, Felix; Gaunt, Adam; Tsyben, Anastasia; Chia, Ming Li; Hesse, Friederike; Wright, Alan J.; Brindle, Kevin M.
- 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.
- Subjects
SPIN excitations; COST functions; MAGNETIC fields; PROTONS; UNIFORMITY
- Publication
Magnetic Resonance in Medicine, 2022, Vol 87, Issue 5, p2130
- ISSN
0740-3194
- Publication type
Article
- DOI
10.1002/mrm.29110