Volume 80, Issue 6 pp. 2538-2548
Full Paper

Effect of head motion on MRI B0 field distribution

Jiaen Liu

Corresponding Author

Jiaen Liu

Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

Correspondence Jiaen Liu, Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10, Room B1D-728, Bethesda, MD 20892. Email: [email protected]Search for more papers by this author
Jacco A. de Zwart

Jacco A. de Zwart

Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

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Peter van Gelderen

Peter van Gelderen

Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

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Joseph Murphy-Boesch

Joseph Murphy-Boesch

Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

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Jeff H. Duyn

Jeff H. Duyn

Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

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First published: 16 May 2018
Citations: 45

Funding information: Intramural Research Program of the National Institute of Neurological Disorders and Stroke

Abstract

Purpose

To identify and characterize the sources of B0 field changes due to head motion, to reduce motion sensitivity in human brain MRI.

Methods

B0 fields were measured in 5 healthy human volunteers at various head poses. After measurement of the total field, the field originating from the subject was calculated by subtracting the external field generated by the magnet and shims. A subject-specific susceptibility model was created to quantify the contribution of the head and torso. The spatial complexity of the field changes was analyzed using spherical harmonic expansion.

Results

Minor head pose changes can cause substantial and spatially complex field changes in the brain. For rotations and translations of approximately 5 º and 5 mm, respectively, at 7 T, the field change that is associated with the subject's magnetization generates a standard deviation (SD) of about 10 Hz over the brain. The stationary torso contributes to this subject-associated field change significantly with a SD of about 5 Hz. The subject-associated change leads to image-corrupting phase errors in multi-shot urn:x-wiley:07403194:media:mrm27339:mrm27339-math-0001-weighted acquisitions.

Conclusion

The B0 field changes arising from head motion are problematic for multishot urn:x-wiley:07403194:media:mrm27339:mrm27339-math-0002-weighted imaging. Characterization of the underlying sources provides new insights into mitigation strategies, which may benefit from individualized predictive field models in addition to real-time field monitoring and correction strategies.

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