Design of broadband RF pulses with polynomial-phase response

R. F. Schulte, A. Henning, J. Tsao, P. Boesiger, K. P. Pruessmann

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The achievable bandwidth of common linear-phase RF pulses is limited by the maximum feasible B1 amplitude of the MR system. It has been shown previously, that this limitation can be circumvented by overlaying a quadratic phase in the frequency domain, which spreads the power across the pulse duration. Quadratic-phase RF pulses are near optimal in terms of achieving minimal B1max. In this work, it is demonstrated that further B1max reduction can be achieved by combining quadratic with higher-order polynomial-phase functions. RF pulses with a phase response up to tenth order were designed using the Shinnar-Le Roux transformation, yielding considerable increases in bandwidth and selectivity as compared to pure quadratic-phase pulses. These benefits are studied for a range of pulse specifications and demonstrated experimentally. For B1max = 20 μT and a pulse duration of 2.1 ms, it was possible to increase the bandwidth from 3.1 kHz for linear and 3.8 kHz for a quadratic to 9.9 kHz for a polynomial-phase pulse.

Original languageEnglish (US)
Pages (from-to)167-175
Number of pages9
JournalJournal of Magnetic Resonance
Volume186
Issue number2
DOIs
StatePublished - Jun 1 2007
Externally publishedYes

Keywords

  • Broadband RF pulses
  • Polynomial-phase pulses
  • Shinnar-Le Roux transformation
  • Very selective saturation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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