title: Advancing RF pulse design using an open-competition format: Report from the 2015 ISMRM challenge.
abstract: To advance the best solutions to two important RF pulse design problems with an open head-to-head competition.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors: Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.|Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
authors: William A
authors: WA
authors: Grissom
authors: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors: Kawin
authors: K
authors: Setsompop
authors: Synaptive Medical, Toronto, Ontario, Canada.
authors: Samuel A
authors: SA
authors: Hurley
authors: McKinsey & Company, Boston, Massachusetts, USA.
authors: Jeffrey
authors: J
authors: Tsao
authors: Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.
authors: Julia V
authors: JV
authors: Velikina
authors: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors: Alexey A
authors: AA
authors: Samsonov
mesh_terms: D000465:Algorithms; D035843:Biomedical Research; D001921:Brain / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*
keywords: RF pulse design; open challenge; optimization; parallel transmission; selective excitation; simultaneous multislice imaging; ultra-high field MRI