Spectrally selective B1-insensitive T2 magnetization preparation sequence

Magn Reson Med. 2009 Jun;61(6):1326-35. doi: 10.1002/mrm.21742.

Abstract

A T(2) magnetization-preparation (T(2) Prep) sequence is proposed that is insensitive to B(1) field variations and simultaneously provides fat suppression without any further increase in specific absorption rate (SAR). Increased B(1) inhomogeneity at higher magnetic field strength (B(0) > or = 3T) necessitates a preparation sequence that is less sensitive to B(1) variations. For the proposed technique, T(2) weighting in the image is achieved using a segmented B(1)-insensitive rotation (BIR-4) adiabatic pulse by inserting two equally long delays, one after the initial reverse adiabatic half passage (AHP), and the other before the final AHP segment of a BIR-4 pulse. This sequence yields T(2) weighting with both B(1) and B(0) insensitivity. To simultaneously suppress fat signal (at the cost of B(0) insensitivity), the second delay is prolonged so that fat accumulates additional phase due to its chemical shift. Numerical simulations as well as phantom and in vivo image acquisitions were performed to show the efficacy of the proposed technique.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Algorithms*
  • Brain / anatomy & histology*
  • Brain Chemistry*
  • Humans
  • Image Interpretation, Computer-Assisted / methods*
  • Magnetic Resonance Imaging / instrumentation
  • Magnetic Resonance Imaging / methods*
  • Magnetic Resonance Spectroscopy / methods*
  • Phantoms, Imaging
  • Radio Waves
  • Signal Processing, Computer-Assisted*