The cost of parallel imaging in functional MRI of the human brain

Lütcke, Henry; Merboldt, Klaus-Dietmar; Frahm, Jens

doi:10.1016/j.mri.2005.10.028

Next »Magnetic Resonance Imaging
Volume 24, Issue 1 , Pages 1-5, January 2006

The cost of parallel imaging in functional MRI of the human brain

Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für Biophysikalische Chemie, 37070 Göttingen, Germany

Received 30 June 2005; received in revised form 31 October 2005; accepted 31 October 2005. published online 19 December 2005.

Abstract

While the advantages of parallel acquisition techniques for echo-planar imaging (EPI) are well documented for studies affected by magnetic field inhomogeneities, this work focuses on the costs in functional MRI of brain regions without artifacts due to susceptibility effects. For a visual stimulation paradigm and relative to conventional EPI (2.9 T; TR/TE=2000/36 ms), the use of parallel acquisition at a reduction factor of 2 decreased the mean number of activated voxels by 21% at 2×2×2-mm³ resolution (n=6) and by 15% at 3×3×3-mm³ resolution (n=6). The loss of sensitivity reflects both a decreased signal-to-noise ratio of the native images due to a lower number of contributing gradient echoes and a decreased BOLD MRI sensitivity due to the coverage of a smaller range of TEs.

Keywords: Magnetic resonance imaging, Parallel acquisitions, Echo-planar imaging, Functional brain mapping