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Repetition time in echo planar functional MRI
Author(s) -
Constable R. Todd,
Spencer Dennis D.
Publication year - 2001
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.1253
Subject(s) - echo time , computer science , functional imaging , echo planar imaging , set (abstract data type) , signal (programming language) , statistical power , echo (communications protocol) , pattern recognition (psychology) , artificial intelligence , magnetic resonance imaging , mathematics , neuroscience , statistics , psychology , medicine , computer network , radiology , programming language
Abstract To date, surprisingly little attention has been directed toward determining the optimum TR in a functional imaging experiment. A survey of the literature reveals a wide range of TRs, but little justification for a specific TR. Long‐TR functional imaging experiments provide maximum signal‐to‐noise ratio (SNR) in the raw images; allow for the collection of a large number of slice locations; and decrease the size of the data set acquired, simplifying storage and handling. This work, however, demonstrates that long‐TR imaging sacrifices statistical power when the paradigm timing is held fixed. That is, for a fixed‐run duration consisting of multiple activation/control blocks, shorter TR acquisitions (on the order of 1000 ms) provide better discrimination between the activated and nonactivated brain tissue regions than do long‐TR acquisitions (on the order of 4000 ms). Results are shown for modeling the functional imaging experiment and for three different paradigms performed on normal subjects. Magn Reson Med 46:748–755, 2001. © 2001 Wiley‐Liss, Inc.