Variable slew-rate spiral design: Theory and application to peak B 1 amplitude reduction in 2D RF pulse design

Dan Xu, Kevin F. King, Zhi Pei Liang

Research output: Contribution to journalArticlepeer-review


A new class of spiral trajectories called variable slew-rate spirals is proposed. The governing differential equations for a variable slew-rate spiral are derived, and both numeric and analytic solutions to the equations are given. The primary application of variable slew-rate spirals is peak B1 amplitude reduction in 2D RF pulse design. The reduction of peak B1 amplitude is achieved by changing the gradient slew-rate profile, and gradient amplitude and slew-rate constraints are inherently satisfied by the design of variable slew-rate spiral gradient waveforms. A design example of 2D RF pulses is given, which shows that under the same hardware constraints the RF pulse using a properly chosen variable slew-rate spiral trajectory can be much shorter than that using a conventional constant slew-rate spiral trajectory, thus having greater immunity to resonance frequency offsets.

Original languageEnglish (US)
Pages (from-to)835-842
Number of pages8
JournalMagnetic Resonance in Medicine
Issue number4
StatePublished - Oct 2007


  • RF pulse design
  • Slew rate
  • Spiral

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

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