Effects of white matter microstructure on phase and susceptibility maps

Wharton, Samuel; Bowtell, Richard W.

Abstract

Purpose: To investigate the effects on quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI) of the frequency variation produced by the microstructure of white matter (WM).

Methods: The frequency offsets in a WM tissue sample that are not explained by the effect of bulk isotropic or anisotropic magnetic susceptibility, but rather result from the local microstructure, were characterized for the first time. QSM and STI were then applied to simulated frequency maps that were calculated using a digitized whole-brain, WM model formed from anatomical and diffusion tensor imaging data acquired from a volunteer. In this model, the magnitudes of the frequency contributions due to anisotropy and microstructure were derived from the results of the tissue experiments.

Results: The simulations suggest that the frequency contribution of microstructure is much larger than that due to bulk effects of anisotropic magnetic susceptibility. In QSM, the microstructure contribution introduced artificial WM heterogeneity. For the STI processing, the microstructure contribution caused the susceptibility anisotropy to be significantly overestimated.

Conclusion: Microstructure-related phase offsets in WM yield artifacts in the calculated susceptibility maps. If susceptibility mapping is to become a robust MRI technique, further research should be carried out to reduce the confounding effects of microstructure-related frequency contributions

Citation

Wharton, S., & Bowtell, R. W. (in press). Effects of white matter microstructure on phase and susceptibility maps. Magnetic Resonance in Medicine, 173(3), https://doi.org/10.1002/mrm.25189

• Journal Article Type: Article
• Acceptance Date: Feb 3, 2014
• Online Publication Date: Feb 18, 2015
• Deposit Date: Jun 30, 2016
• Publicly Available Date: Jun 30, 2016
• Journal: Magnetic Resonance in Medicine
• Print ISSN: 0740-3194
• Electronic ISSN: 1522-2594
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 173
• Issue: 3
• DOI: https://doi.org/10.1002/mrm.25189
• Keywords: Quantitative susceptibility mapping; phase imaging; microstructure; white matter; anisotropy; gradient echo MRI
• Public URL: https://nottingham-repository.worktribe.com/output/744899
• Publisher URL: http://onlinelibrary.wiley.com/doi/10.1002/mrm.25189/abstract
• Contract Date: Jun 30, 2016