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Updated: May 2, 2026

Fat-Water Phantoms for Magnetic Resonance Imaging Validation: A Flexible and Scalable Protocol
Published on: September 7, 2018
Improving chemical shift encoded water-fat separation using object-based information of the magnetic field
Samir D Sharma1, Nathan S Artz, Diego Hernando
1Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
Purpose:
The purpose of this work was to improve the robustness of existing chemical shift encoded water-fat separation methods by incorporating object-based information of the B0 field inhomogeneity.
Theory:
The primary challenge in water-fat separation is the estimation of phase shifts that arise from B0 field inhomogeneity, which is composed of the background field and susceptibility-induced field. The susceptibility-induced field can be estimated if the susceptibility distribution is known or can be approximated. In this work, the susceptibility distribution is approximated from the source images using the known susceptibility values of water, fat, and air. The field estimate is then demodulated from the source images before water-fat separation.
Methods:
Chemical shift encoded source images were acquired in anatomical regions that are prone to water-fat swaps. The images were processed using algorithms from the ISMRM Fat-Water Toolbox, with and without the object-based field map information. The estimates were compared to examine the benefit of using the object-based field map information.
Results:
Multiple cases are shown in which water-fat swaps were avoided by using the object-based information of the B0 field map.
Conclusion:
Object-based information of the B0 field may improve the robustness of existing chemical shift encoded water-fat separation methods.
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