Full Paper

Variable-rate selective excitation for rapid MRI sequences

  1. Brian A. Hargreaves*,
  2. Charles H. Cunningham,
  3. Dwight G. Nishimura,
  4. Steven M. Conolly

Article first published online: 23 AUG 2004

DOI: 10.1002/mrm.20168

Issue

Magnetic Resonance in Medicine

Magnetic Resonance in Medicine

Volume 52, Issue 3, pages 590–597, September 2004

Additional Information

How to Cite

Hargreaves, B. A., Cunningham, C. H., Nishimura, D. G. and Conolly, S. M. (2004), Variable-rate selective excitation for rapid MRI sequences. Magnetic Resonance in Medicine, 52: 590–597. doi: 10.1002/mrm.20168

Author Information

  1. Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California

*Room 216, Packard Electrical Engineering Bldg., Stanford, CA 94305-9510

Publication History

  1. Issue published online: 23 AUG 2004
  2. Article first published online: 23 AUG 2004
  3. Manuscript Accepted: 1 APR 2004
  4. Manuscript Revised: 24 MAR 2004
  5. Manuscript Received: 18 FEB 2004

Funded by

  • NIH. Grant Numbers: HL39297, HL56394, AR46904, CA50948, EB000346, EB000777-01
  • State of California. Grant Number: TRDRP 9RT-0024
  • GE Med-ical Systems

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Keywords:

  • selective excitation;
  • VERSE;
  • SSFP;
  • rapid imaging;
  • True-FISP

Abstract

Balanced steady-state free precession (SSFP) imaging sequences require short repetition times (TRs) to avoid off-resonance artifacts. The use of slab-selective excitations is common, as this can improve imaging speed by limiting the field of view (FOV). However, the necessarily short-duration excitations have poor slab profiles. This results in unusable slices at the slab edge due to significant flip-angle variations or aliasing in the slab direction. Variable-rate selective excitation (VERSE) is a technique by which a time-varying gradient waveform is combined with a modified RF waveform to provide the same excitation profile with different RF power and duration characteristics. With the use of VERSE, it is possible to design short-duration pulses with dramatically improved slab profiles. These pulses achieve high flip angles with only minor off-resonance sensitivity, while meeting SAR limits at 1.5 T. The improved slab profiles will enable more rapid 3D imaging of limited volumes, with more consistent image contrast across the excited slab. Magn Reson Med 52:590–597, 2004. © 2004 Wiley-Liss, Inc.

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