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An estimation and correction scheme for system imperfections in multiple‐echo magnetic resonance imaging
Author(s) -
Majumdar S.,
Gmitro A.,
Orphanoudakis S. C.,
Reddy D.,
Gore J. C.
Publication year - 1987
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.1910040302
Subject(s) - echo time , computer science , echo (communications protocol) , field (mathematics) , scheme (mathematics) , spin echo , image quality , artificial intelligence , computer vision , algorithm , magnetic resonance imaging , image (mathematics) , mathematics , mathematical analysis , medicine , computer network , pure mathematics , radiology
Multiecho sequences are widely used in MRI because they are an efficient means of acquiring data and they can be used to quantitatively estimate T 2 . However, the uniformity of each image and the accuracy of each T 2 estimate may be corrupted by several instrumental factors such as rf pulse imperfections and static field inhomogeneities. We propose a scheme based on our prior knowledge of the effects of such factors and using the Lexenberg‐Marquardt method of nonlinear estimation that produces accurate estimates of T 2 even in the presence of substantial system imperfections and improves the image quality of later echo images in a multiecho sequence. A further extension of this scheme permits mapping the distribution of the static magnetic field from a single multiecho imaging study of a uniform object. Simulations have been performed to test the efficacy of this scheme and the results are substantiated with experiments performed on a whole‐body imager operating at 6.35 MHz. © 1987 Academic Press, Inc.