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Echo time optimization for linear combination myelin imaging
Author(s) -
Vidarsson Logi,
Conolly Steven M.,
Lim Kelvin O.,
Gold Garry E.,
Pauly John M.
Publication year - 2005
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.20360
Subject(s) - myelin , imaging phantom , white matter , echo (communications protocol) , multislice , nuclear magnetic resonance , in vivo , biomedical engineering , chemistry , magnetic resonance imaging , nuclear medicine , materials science , physics , computer science , medicine , biology , radiology , central nervous system , neuroscience , computer network , microbiology and biotechnology
Abstract A 3‐echo linear combination myelin imaging method is presented. The echo times and weights are chosen such that the signal‐to‐noise ratio (SNR) of myelin–water is maximized, and signals from other white matter components are sufficiently suppressed. Interfering tissue water and cerebrospinal fluid (CSF) signals are much stronger than myelin due to their longer T 2 and abundance. By carefully optimizing the echo times a 50‐fold tissue water suppression is achieved along with a 10‐fold CSF suppression. For comparison 4, 5, and 32 echo filters are also designed using the same method. The SNR efficiency of these filters is very similar. The 3‐echo filter design was validated by phantom scans. In addition, multislice in vivo myelin images were acquired from both a healthy volunteer and a multiple sclerosis patient. Total scan time was 5 min. A uniform T 2 filter is also designed to pass all white matter species with uniform gain. The myelin–water fraction of the in vivo 3‐echo data set is then measured by dividing the myelin image by the uniformly filtered image. Obtained myelin–water fractions compare well with previous work. Magn Reson Med 53:398–407, 2005. © 2005 Wiley‐Liss, Inc.