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Transient signal changes in diffusion‐weighted stimulated echoes during neuronal stimulation at 3T
Author(s) -
Goerke Ute,
Möller Harald E.
Publication year - 2007
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.20891
Subject(s) - nuclear magnetic resonance , stimulus (psychology) , physics , voxel , time constant , signal (programming language) , transient (computer programming) , neuroscience , computer science , biology , psychology , artificial intelligence , electrical engineering , psychotherapist , programming language , engineering , operating system
Purpose To develop a sensitive method for detecting minute transient signal changes that can arise due to variations in the extravascular apparent self‐diffusion coefficient, D , during neuronal activation. Materials and Methods A three‐pulse sequence that reads out a moderately diffusion‐weighted (DW) primary echo (PRE) and a heavily DW stimulated echo (STE) was employed to investigate whether small transient signal changes in extravascular D occur in response to a visual stimulus. Contributions to signal changes caused by subtle differences in the transient variations of the apparent transverse relaxation constant, T 2 , between the PRE and STE were also quantified. Results On z ‐maps obtained from the STE, more voxels showed significant stimulus‐related signal changes compared to maps of the PRE. The average maximum signal change of the STE was larger than that of the PRE. The observed increase in the relative signal change was independent of the strength of the diffusion weighting. Conclusion The STE is more sensitive to neuronal activity than the PRE. The discrepancy between the two echoes does not arise from transient changes in D , but from subtle differences in stimulus‐related variations of T 2 between the two echoes. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.