Impact of reduced k-space acquisition on pathologic detectability for volumetric MR spectroscopic imaging

Mohammad Sabati, Jiping Zhan, Varan Govind, Kristopher Arheart, Andrew A Maudsley

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Purpose To assess the impact of accelerated acquisitions on the spectral quality of volumetric magnetic resonance spectroscopic imaging (MRSI) and to evaluate their ability in detecting metabolic changes with mild injury. Materials and Methods The implementation of a generalized autocalibrating partially parallel acquisition (GRAPPA) method for a high-resolution whole-brain echo planar SI (3D-EPSI) sequence is first described and the spectral accuracy of the GRAPPA-EPSI method is investigated using lobar and voxel-based analyses for normal subjects and patients with mild traumatic brain injuries (mTBI). The performance of GRAPPA was compared with that of fully encoded EPSI for five datasets collected from normal subjects at the same scanning session, as well as on 45 scans (20 normal subjects and 25 mTBI patients) for which the reduced k-space sampling was simulated. For comparison, a central k-space lower-resolution 3D-EPSI acquisition was also simulated. Differences in individual metabolites and metabolite ratio distributions of the mTBI group relative to those of age-matched control subjects were statistically evaluated using analyses divided into hemispheric brain lobes and tissue types. Results GRAPPA-EPSI with 16-minute scan time yielded robust and similar results in terms of MRSI quantitation, spectral fitting, and accuracy with that of fully sampled 3D-EPSI acquisitions and was more accurate than central k-space acquisition. Primary findings included high correlations (accuracy of 92.6%) between the GRAPPA and fully sampled results. Conclusion Although the reduced encoding method is associated with lower signal-to-noise ratio (SNR) that impacts the quality of spectral analysis, the use of the parallel imaging method can lead to the same diagnostic outcomes as the fully sampled data when using the sensitivity-limited volumetric MRSI. J. Magn. Reson. Imaging 2014;39:224-234. © 2013 Wiley Periodicals, Inc.

Original languageEnglish
Pages (from-to)224-234
Number of pages11
JournalJournal of Magnetic Resonance Imaging
Volume39
Issue number1
DOIs
StatePublished - Jan 1 2014

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Brain Concussion
Magnetic Resonance Imaging
Aptitude
Brain
Signal-To-Noise Ratio
Individuality
Wounds and Injuries

Keywords

  • clinical equivalency
  • MR spectroscopic imaging
  • parallel imaging
  • traumatic brain injury
  • undersampled acquisition

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Impact of reduced k-space acquisition on pathologic detectability for volumetric MR spectroscopic imaging. / Sabati, Mohammad; Zhan, Jiping; Govind, Varan; Arheart, Kristopher; Maudsley, Andrew A.

In: Journal of Magnetic Resonance Imaging, Vol. 39, No. 1, 01.01.2014, p. 224-234.

Research output: Contribution to journalArticle

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abstract = "Purpose To assess the impact of accelerated acquisitions on the spectral quality of volumetric magnetic resonance spectroscopic imaging (MRSI) and to evaluate their ability in detecting metabolic changes with mild injury. Materials and Methods The implementation of a generalized autocalibrating partially parallel acquisition (GRAPPA) method for a high-resolution whole-brain echo planar SI (3D-EPSI) sequence is first described and the spectral accuracy of the GRAPPA-EPSI method is investigated using lobar and voxel-based analyses for normal subjects and patients with mild traumatic brain injuries (mTBI). The performance of GRAPPA was compared with that of fully encoded EPSI for five datasets collected from normal subjects at the same scanning session, as well as on 45 scans (20 normal subjects and 25 mTBI patients) for which the reduced k-space sampling was simulated. For comparison, a central k-space lower-resolution 3D-EPSI acquisition was also simulated. Differences in individual metabolites and metabolite ratio distributions of the mTBI group relative to those of age-matched control subjects were statistically evaluated using analyses divided into hemispheric brain lobes and tissue types. Results GRAPPA-EPSI with 16-minute scan time yielded robust and similar results in terms of MRSI quantitation, spectral fitting, and accuracy with that of fully sampled 3D-EPSI acquisitions and was more accurate than central k-space acquisition. Primary findings included high correlations (accuracy of 92.6{\%}) between the GRAPPA and fully sampled results. Conclusion Although the reduced encoding method is associated with lower signal-to-noise ratio (SNR) that impacts the quality of spectral analysis, the use of the parallel imaging method can lead to the same diagnostic outcomes as the fully sampled data when using the sensitivity-limited volumetric MRSI. J. Magn. Reson. Imaging 2014;39:224-234. {\circledC} 2013 Wiley Periodicals, Inc.",
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