Spectroscopic imaging with volume selection by unpaired adiabatic π pulses: Theory and application

Julien Valette, Jang Yeon Park, Olli Gröhn, Kamil Uǧurbil, Michael Garwood, Pierre Gilles Henry

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

In NMR spectroscopy, volume selection can be advantageously achieved using adiabatic π pulses, which enable high bandwidth and B1 insensitivity. In order to avoid the generation of non-linear phase profiles and the subsequent signal loss caused by incoherent averaging, adiabatic π pulses are usually used in pairs for volume selection in each spatial dimension. Alternatively, when performing spectroscopic imaging (SI), a high enough spatial resolution results in negligible phase dispersion within each pixel. This allows using only one pulse per selected spatial dimension, resulting in a reduced echo-time and reduced power deposition. In this work, the feasibility of such an approach is explored theoretically and numerically, allowing the derivation of explicit conditions to obtain SI images without artifact. Adequate spatial and spectral post-processing procedures are described to compensate for the effect of non-linear phase profiles. These developments are applied to SI in the rat brain at 9.4 T, using a new adiabatic sequence named Pseudo-LASER.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalJournal of Magnetic Resonance
Volume189
Issue number1
DOIs
StatePublished - Nov 1 2007

Keywords

  • Adiabatic pulse
  • Non-linear phase
  • Reconstruction
  • Spatial response function
  • Spectroscopic imaging

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