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High resolution SE-fMRI in humans at 3 and 7 T using a motor task

  • Andreas Schäfer
  • Wietske van der Zwaag
  • Susan T. Francis
  • Kay E. Head
  • Penny A. Gowland
  • Richard W. BowtellEmail author
Research Article

Abstract

Object

The sensitivity of spin echo (SE) experiments to blood oxygenation level dependent (BOLD) contrast was explored in a study of the same six subjects carried out at 3 and 7 T.

Materials and methods

Multi-slice, single shot, spin echo, echo planar images with a voxel size of 1 ×  1 ×  3 mm3 were acquired at three different echo times, during execution of a simple motor task.

Results

Significant activation was observed at all echo times at both field strengths. Analysis of the fractional signal change as a function of echo time indicated that the change in relaxation rate, ΔR 2, at 7 T was 0.51 ± 0.14 s , which was 1.3 times larger than the value found at 3 T. Measurements of the percentage signal change on activation and temporal signal to noise ratio showed that there was an increase in the BOLD contrast to noise ratio (CNR) at 7 versus 3 T by a factor of 1.9. There was no overlap of areas of significant activation in the SE data acquired at either field strength with the site of large veins.

Conclusion

SE-BOLD CNR in motor cortex was found to increase significantly at 7 T compared with 3 T.

Keywords

BOLD High resolution High field fMRI Spin echo SE 

Abbreviations

BOLD

Blood oxygenation level dependent

CBV

Regional blood volume

CBF

Cerebral blood flow

CMRO2

Cerebral metabolic consumption rate

CNR

Contrast-to-noise ratio

SNR

Signal-to-noise ratio

EPI

Echo planar imaging

fMRI

Functional magnetic resonance imaging

FOV

Field of view

GM

Grey matter

GE

Gradient echo

SE

Spin echo

ROI

Region of interest

OVS

Outer volume suppression

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Copyright information

© ESMRMB 2007

Authors and Affiliations

  • Andreas Schäfer
    • 1
  • Wietske van der Zwaag
    • 1
  • Susan T. Francis
    • 1
  • Kay E. Head
    • 1
  • Penny A. Gowland
    • 1
  • Richard W. Bowtell
    • 1
    Email author
  1. 1.Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and AstronomyUniversity of NottinghamNottinghamUK

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