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

Research output: Contribution to journalArticlepeer-review

117 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 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.

Original languageEnglish
Pages (from-to)68-74
Number of pages7
JournalJournal of Magnetic Resonance
Volume167
Issue number1
DOIs
StatePublished - Mar 2004

Keywords

  • BEBOP
  • Broadband excitation
  • Optimal control theory

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