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Data consistency‐driven determination of B 0 ‐fluctuations in gradient‐echo MRI
Author(s) -
Meineke Jakob,
Nielsen Tim
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.27630
Subject(s) - amplitude , consistency (knowledge bases) , homogeneity (statistics) , echo (communications protocol) , gradient echo , sensitivity (control systems) , data consistency , phase (matter) , computer science , physics , mathematics , artificial intelligence , magnetic resonance imaging , optics , statistics , medicine , computer network , quantum mechanics , electronic engineering , radiology , engineering , operating system
Purpose Introduce a method to estimate B 0 ‐fluctuations based on the analysis of raw k‐space data, without sequence modifications or external hardware, and correct for their detrimental effects in gradient‐echo MRI. Theory Inconsistencies in multi‐channel raw k‐space data can be used to estimate B 0 ‐fluctuations by exploiting coil‐sensitivity information. Methods The proposed method, dubbed consistency navigation, is used to extract B 0 ‐fluctuations from T 2 * ‐weighted 3D gradient‐echo data. These results are compared with the results from an MR phase navigator and respiratory bellows. The spatial variation of the B 0 ‐fluctuation amplitude is derived using the sensitivity maps of the coil array and compared with direct measurements based on dynamic 2D gradient‐echo data. ResultsB 0 ‐fluctuations derived from the consistency navigator and MR phase navigator are highly correlated. Images corrected for these fluctuations show marked improvements in homogeneity and tissue delineation. The spatial variation of the B 0 ‐fluctuation amplitude follows closely the variation directly measured from time‐resolved 2D scans. Conclusions Based on the consistency navigator, an accurate estimation of the spatiotemporal characteristics of B 0 ‐fluctuations and correction of T 2 * ‐weighted images has been demonstrated.