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On the artifact of a subvoxel susceptibility deviation in spoiled gradient‐echo imaging
Author(s) -
Bos Clemens,
Viergever Max A.,
Bakker Chris J.G.
Publication year - 2003
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.10505
Subject(s) - artifact (error) , dephasing , orientation (vector space) , echo (communications protocol) , nuclear magnetic resonance , displacement (psychology) , physics , signal (programming language) , position (finance) , spin echo , gradient echo , echo time , moment (physics) , pulse sequence , magnetic resonance imaging , computer vision , computer science , mathematics , geometry , programming language , medicine , psychology , computer network , finance , classical mechanics , quantum mechanics , psychotherapist , economics , radiology
In MRI, susceptibility‐based negative contrast amplifies the effect of objects that are too small to be detected by water displacement or intrinsic contrast properties. In this work, a simplified description of the susceptibility artifact of a subvoxel object in spoiled gradient‐echo imaging is presented that focuses on the elimination of signal in its vicinity: the dephased‐volume. The size and position of the dephased‐volume are investigated using 3D time‐domain simulations and in vitro experiments in which scan parameters and object magnetic moment are systematically varied. Overall signal loss is found to be linearly related to a dephasing parameter that contains the susceptibility difference with tissue, object volume, and echo time (TE), and thus allows the magnetic moment of the object to be assessed. Gradient strength, in‐plane resolution, fractional echo, and slice orientation have limited influence. For the settings used, the center of mass of the artifact was always within 0.5 mm of the object's in‐plane position. Magn Reson Med 50:400–404, 2003. © 2003 Wiley‐Liss, Inc.