Accelerated imaging with segmented 2D pulses using parallel imaging and virtual coils

Michael Mullen, Alexander Gutierrez, Naoharu Kobayashi, Jarvis D Haupt, Michael Garwood

Research output: Contribution to journalArticle

Abstract

Large magnetic field inhomogeneity can be a significant cause of spatial flip-angle variation when using ordinary, limited-bandwidth RF pulses. Multidimensional RF pulses are particularly sensitive to inhomogeneity due to their extended pulse length, which decreases their bandwidth. Previously, it was shown that, by breaking a 2D pulse into multiple undersampled k-space segments, the excitation bandwidth can be increased at the expense of increased imaging time. The present study shows how this increased imaging time can be offset by undersampling acquisition k-space in a phase-encoded dimension that is in the direction of excitation segmentation. Data from each segment are viewed as originating from “virtual receive coils” rather than multiple physical coils. The undersampled data are reconstructed using parallel imaging techniques (e.g. as in GRAPPA). The method was tested in vivo with brain imaging at both 3 T and 4 T, and used in conjunction with a 32-channel head coil and conventional GRAPPA on the 3 T data. Relationships with existing techniques and future applications are discussed.

Original languageEnglish (US)
Pages (from-to)185-194
Number of pages10
JournalJournal of Magnetic Resonance
Volume305
DOIs
StatePublished - Aug 1 2019

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coils
Imaging techniques
Magnetic Fields
pulses
bandwidth
Bandwidth
Neuroimaging
inhomogeneity
Head
imaging techniques
excitation
brain
Brain
acquisition
Magnetic fields
causes
magnetic fields
Direction compound

Keywords

  • 2D pulse
  • B inhomogeneity
  • Frequency-modulated
  • GRAPPA
  • MRI
  • Parallel imaging
  • Segmented pulse
  • Virtual coil

PubMed: MeSH publication types

  • Journal Article

Cite this

Accelerated imaging with segmented 2D pulses using parallel imaging and virtual coils. / Mullen, Michael; Gutierrez, Alexander; Kobayashi, Naoharu; Haupt, Jarvis D; Garwood, Michael.

In: Journal of Magnetic Resonance, Vol. 305, 01.08.2019, p. 185-194.

Research output: Contribution to journalArticle

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