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Functional magnetic resonance imaging with intermolecular double‐quantum coherences at 3 T
Author(s) -
Schäfer Andreas,
Jochimsen Thies H.,
Möller Harald E.
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.20506
Subject(s) - dephasing , nuclear magnetic resonance , spin echo , functional magnetic resonance imaging , flip angle , coherence (philosophical gambling strategy) , pulse sequence , magnetic resonance imaging , blood oxygen level dependent , relaxation (psychology) , chemistry , physics , neuroscience , psychology , quantum mechanics , medicine , radiology
Functional magnetic resonance imaging (fMRI) based on the selection of intermolecular double‐quantum coherences (iDQC) was performed with a standard birdcage coil at 3 T in a group of normal human volunteers. Suppression of spurious signal contributions from unwanted coherence‐transfer pathways was achieved by combining a two‐step phase cycle and a long repetition time of 5 s. A gradient‐recalled echo iDQC sequence (echo time, T E = 80 ms) yielded robust activation with a visual paradigm. Maximum z ‐scores were about half of those observed with conventional blood‐oxygen level dependent fMRI, whereas the functional signal change increased by more than a factor of 5. No activation was obtained with a spin‐echo iDQC sequence ( T E = 160 ms), in which dephasing accumulated during the evolution period was fully rephased by an appropriate delay time. It is hypothesized that substantial inherent diffusion weighting of the iDQC technique efficiently suppresses intravascular contributions to the functional contrast. A consistent quantitative explanation of the observed amount of signal change currently remains speculative. Magn Reson Med 53:1402–1408, 2005. © 2005 Wiley‐Liss, Inc.