Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2011-1-24
pubmed:abstractText
The characterisation of the extravascular (EV) contribution to the blood oxygenation level-dependent (BOLD) effect is important for understanding the spatial specificity of BOLD contrast and for modelling approaches that aim to extract quantitative metabolic parameters from the BOLD signal. Using bipolar crusher gradients, total (b?=?0?s/mm(2) ) and predominantly EV (b?=?100?s/mm(2) ) gradient echo BOLD ?R(2)* and signal changes (?S/S) in response to visual stimulation (flashing checkerboard; f?=?8?Hz) were investigated sequentially (within?<?3?h) at 1.5, 3.0 and 7.0 T in the same subgroup of healthy volunteers (n?=?7) and at identical spatial resolutions (3.5?×?3.5?×?3.5?mm(3)). Total ?R(2)* (z-score analysis) values were -0.61?±?0.10?s(-1) (1.5 T), -0.74?±?0.05?s(-1) (3.0 T) and -1.37?±?0.12?s(-1) (7.0 T), whereas EV ?R(2)* values were -0.28?±?0.07?s(-1) (1.5 T), -0.52?±?0.07?s(-1) (3.0 T) and -1.25?±?0.11?s(-1) (7.0 T). Although EV ?R(2)* increased linearly with field, as expected, it was found that EV ?S/S increased less than linearly with field in a manner that varied with TE choice. Furthermore, unlike ?R(2)*, total and EV ?S/S did not converge at 7.0 T. These trends were similar whether a z-score analysis or occipital lobe-based region-of-interest approach was used for voxel selection. These findings suggest that calibrated BOLD approaches may benefit from an EV ?R(2)* measurement as opposed to a ?S/S measurement at a single TE.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1099-1492
pubmed:author
pubmed:copyrightInfo
Copyright © 2010 John Wiley & Sons, Ltd.
pubmed:issnType
Electronic
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
25-34
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Blood oxygenation level-dependent (BOLD) total and extravascular signal changes and ?R2* in human visual cortex at 1.5, 3.0 and 7.0 T.
pubmed:affiliation
FMRIB Centre, Department of Clinical Neurology, University of Oxford, Oxford, UK. mjd@jhu.edu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural