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Advancing RF pulse design using an open‐competition format: Report from the 2015 ISMRM challenge
Author(s) -
Grissom William A.,
Setsompop Kawin,
Hurley Samuel A.,
Tsao Jeffrey,
Velikina Julia V.,
Samsonov Alexey A.
Publication year - 2017
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26512
Subject(s) - pulse (music) , computer science , excitation , multislice , magnetic resonance imaging , pulse sequence , phase (matter) , transmission (telecommunications) , pulse duration , nuclear magnetic resonance , physics , telecommunications , optics , medicine , electrical engineering , engineering , laser , radiology , detector , quantum mechanics
Purpose To advance the best solutions to two important RF pulse design problems with an open head‐to‐head competition. Methods Two sub‐challenges were formulated in which contestants competed to design the shortest simultaneous multislice (SMS) refocusing pulses and slice‐selective parallel transmission (pTx) excitation pulses, subject to realistic hardware and safety constraints. Short refocusing pulses are needed for spin echo SMS imaging at high multiband factors, and short slice‐selective pTx pulses are needed for multislice imaging in ultra‐high field MRI. Each sub‐challenge comprised two phases, in which the first phase posed problems with a low barrier of entry, and the second phase encouraged solutions that performed well in general. The Challenge ran from October 2015 to May 2016. Results The pTx Challenge winners developed a spokes pulse design method that combined variable‐rate selective excitation with an efficient method to enforce SAR constraints, which achieved 10.6 times shorter pulse durations than conventional approaches. The SMS Challenge winners developed a time‐optimal control multiband pulse design algorithm that achieved 5.1 times shorter pulse durations than conventional approaches. Conclusion The Challenge led to rapid step improvements in solutions to significant problems in RF excitation for SMS imaging and ultra‐high field MRI. Magn Reson Med 78:1352–1361, 2017. © 2016 International Society for Magnetic Resonance in Medicine.