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Resolving estimation uncertainties of chemical shift encoded fat‐water imaging using magnetization transfer effect
Author(s) -
Samsonov Alexey,
Liu Fang,
Velikina Julia V.
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27709
Subject(s) - magnetization transfer , magnetization , robustness (evolution) , prior probability , initialization , algorithm , computer science , mathematics , biological system , nuclear magnetic resonance , physics , magnetic field , chemistry , artificial intelligence , bayesian probability , magnetic resonance imaging , biology , gene , radiology , programming language , medicine , biochemistry , quantum mechanics
Purpose B 0 field inhomogeneity may cause significant errors in chemical shift encoding‐based fat‐water (F/W) separation. We describe a new approach to improve its robustness using novel B 0 field map pre‐estimation. Methods Our method exploits insensitivity of fat to magnetization transfer effect, which allows generating fat‐insensitive B 0 field priors with full or partial spatial support using a low‐resolution magnetization transfer‐weighted scan. The full prior can be employed by most F/W separation methods for initialization or data demodulation. We also propose a modified region‐growing algorithm in which the partial prior is utilized for its initial seeding. Results The magnetization transfer‐based B 0 priors significantly reduced F/W errors of three representative F/W separation methods in all cases. In cases with moderate B 0 inhomogeneity, the full prior allowed error‐free separation even with basic, voxel‐independent processing. When coupled with methods exploiting B 0 field smoothness, it significantly improved separation accuracy even in the presence of strong inhomogeneities. Seeding the region‐growing with the partial prior significantly improved performance of F/W separation, including cases with spatially disconnected tissues. Conclusion Magnetization transfer‐based B 0 field pre‐estimation provides valuable prior information for F/W separation, which may significantly improve its robustness at the expense of nominal (< 5%‐10%) scan time increase.