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Cortical depth‐dependent gradient‐echo and spin‐echo BOLD fMRI at 9.4T
Author(s) -
Zhao Fuqiang,
Wang Ping,
Kim SeongGi
Publication year - 2004
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.10720
Subject(s) - echo (communications protocol) , nuclear magnetic resonance , spin echo , gradient echo , fast spin echo , magnetic resonance imaging , physics , computer science , medicine , radiology , computer network
To examine cortical depth‐related spatial specificity and signal changes in gradient‐echo (GE) and spin‐echo (SE) blood oxygenation level‐dependent (BOLD) fMRI signals, a well‐established cat visual stimulation model was used at 9.4T. The GE BOLD signal percent change is the highest at the surface of the cortex containing pial vessels, and decreases as cortical depth increases. In contrast, the SE BOLD signal is more specific to parenchyma, showing the highest signal change in the middle cortical areas. The stimulation‐induced Δ R 2 *to Δ R 2 ratio is dependent on the vessel size, which is related to basal susceptibility effects. The averaged ratio of Δ R 2 *to Δ R 2 in all active regions, including large vessels, is 3.3 ± 0.5 ( N = 6). The averaged ratio of Δ R 2 *to Δ R 2 is 8.8 ± 1.7 ( N = 4) on the surface of the cortex with large pial draining vessels, and decreases to 1.9 ± 0.1 on the middle cortical areas with parenchymal microvessels. Δ R 2 * /Δ R 2 is closely related to basal susceptibility effects and can be used to differentiate tissue from vessel regions. Magn Reson Med 51:518–524, 2004. © 2004 Wiley‐Liss, Inc.