Linked Life Data

15844094

Source:http://linkedlifedata.com/resource/pubmed/id/15844094

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2005-4-26
pubmed:abstractText
Contrast-to-noise ratio (CNR) in blood oxygenation level-dependent (BOLD) based functional MRI (fMRI) studies is a fundamental parameter to determine statistical significance and therefore to map functional activation in the brain. The CNR is defined here as BOLD contrast with respect to temporal fluctuation. In this study, a theoretical noise model based on oxygenation-sensitive MRI signal formation is proposed. No matter what the noise sources may be in the signal acquired by a gradient-echo echo-planar imaging pulse sequence, there are only three noise elements: apparent spin density fluctuations, S(0)(t); transverse relaxation rate fluctuations, R(2) (*)(t); and thermal noise, n(t). The noise contributions from S(0)(t), R(2) (*)(t), and n(t) to voxel time course fluctuations were evaluated as a function of echo time (TE) at 3 T. Both noise contributions caused by S(0)(t) and R(2) (*)(t) are significantly larger than that of thermal noise when TE = 30 ms. In addition, the fluctuations between S(0)(t) and R(2) (*)(t) are cross-correlated and become a noise factor that is large enough and cannot be ignored. The experimentally measured TE dependences of noise, temporal signal-to-noise ratio, and BOLD CNR in finger-tapping activation regions were consistent with the proposed model. Furthermore, the proposed theoretical models not only unified previously proposed BOLD CNR models, but also provided mechanisms for interpreting apparent controversies and limitations that exist in the literature.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0740-3194
pubmed:author
pubmed:copyrightInfo
Copyright 2005 Wiley-Liss, Inc.
pubmed:issnType
Print
pubmed:volume
53
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1046-54
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Theoretical noise model for oxygenation-sensitive magnetic resonance imaging.
pubmed:affiliation
Department of Biophysics, Medical College of Wisconsin, Milwaukee, 53226, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, N.I.H., Extramural