Robust field map generation using a triple-echo acquisition

Windischberger, Christian, Robinson, Simon, Rauscher, Alexander, Barth, Markus and Moser, Ewald (2004) Robust field map generation using a triple-echo acquisition. Journal of Magnetic Resonance Imaging, 20 4: 730-734. doi:10.1002/jmri.20158

Author Windischberger, Christian
Robinson, Simon
Rauscher, Alexander
Barth, Markus
Moser, Ewald
Title Robust field map generation using a triple-echo acquisition
Journal name Journal of Magnetic Resonance Imaging   Check publisher's open access policy
ISSN 1053-1807
Publication date 2004-10-01
Year available 2004
Sub-type Letter to editor, brief commentary or brief communication
DOI 10.1002/jmri.20158
Open Access Status Not yet assessed
Volume 20
Issue 4
Start page 730
End page 734
Total pages 5
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Language eng
Formatted abstract
Purpose: To establish a fast and robust technique for generating magnetic field maps for the correction of geometric distortions in echo-planar magnetic resonance (MR) images.

Materials and Methods: Multislice gradient-echo (GE) images were acquired at echo times of 6, 6.5, and 7.5 msec in order to cover a field shift range of ±666 Hz in the resulting B0 maps. To account for possible phase wrap scenarios, seven phase triples were calculated for each pixel. Linear regression of the phase vs. echo time was performed for each set. The slope of the set with the minimum fitting error was taken as the true magnetic field in the respective pixel.

Results: Based on the fitting error distribution the technique is shown to be feasible and effective for assessing the field distribution in the brain at 3 T, especially in inferior brain areas (amygdalae, hippocampus). Examples of echo-planar images distortion corrected using the calculated field maps are shown.

Conclusion: The approach presented yields robust estimation of magnetic field maps and requires under a minute of additional acquisition time and only seconds of computational time. As such it is easily possible to apply image distortion correction in routine functional MR imaging (fMRI) studies, enabling improved coregistration of brain activation maps with structures on anatomical images.
Keyword Echo-planar imaging
Field mapping
Functional MRI
Geometric distortion
High field MRI
Q-Index Code CX
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Letter to editor, brief commentary or brief communication
Collection: Centre for Advanced Imaging Publications
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