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Motion artifact reduction with three‐point ghost phase cancellation
Author(s) -
Xiang QingSan,
Henkelman R. Mark
Publication year - 1991
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880010604
Subject(s) - artifact (error) , pixel , computer science , signal (programming language) , ideal (ethics) , phase (matter) , artificial intelligence , encoding (memory) , image (mathematics) , computer vision , set (abstract data type) , algorithm , modulation (music) , point (geometry) , physics , mathematics , acoustics , philosophy , geometry , epistemology , quantum mechanics , programming language
A novel method for “ghost” artifact suppression is introduced. It suppresses ghosts induced by motion in any direction, as well as other types of quasi‐periodic signal modulation. Because it requires neither special hardware nor intensive data processing, it can be easily implemented on conventional magnetic resonance (MR) imagers. The method is based on the concept of decomposition of a ghosted complex image into a ghost mask and ideal image. A set of deliberately designed acquisitions are used to generate a set of ghosted complex images in which the ghost components are related in a simple manner. With use of equations describing image decomposition and ghost correlation, the ideal image can be calculated pixel by pixel. The ideal image obtained (representing the time‐averaged spin‐density distribution) is shown to be a truer representation of physical reality than the ghost‐free image obtained with ordered phase encoding. In this technique, both interview and intraview effects are taken into account. The technique is also useful in simultaneously suppressing ghosts from multifrequency signal modulations such as respiratory and cardiac motions. The method was successfully tested with three time‐interleaved, phase‐encoding‐order‐shifted acquisitions. Experimental results have shown that it is a simple but effective technique.