Linked Life Data

21334231

Source:http://linkedlifedata.com/resource/pubmed/id/21334231

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2011-3-28
pubmed:abstractText
A new method entitled Relaxation Along a Fictitious Field (RAFF) was recently introduced for investigating relaxations in rotating frames of rank ? 2. RAFF generates a fictitious field (E) by applying frequency-swept pulses with sine and cosine amplitude and frequency modulation operating in a sub-adiabatic regime. In the present work, MRI contrast is created by varying the orientation of E, i.e. the angle ? between E and the z? axis of the second rotating frame. When ? > 45°, the amplitude of the fictitious field E generated during RAFF is significantly larger than the RF field amplitude used for transmitting the sine/cosine pulses. Relaxation during RAFF was investigated using an invariant-trajectory approach and the Bloch-McConnell formalism. Dipole-dipole interactions between identical (like) spins and anisochronous exchange (e.g., exchange between spins with different chemical shifts) in the fast exchange regime were considered. Experimental verifications were performed in vivo in human and mouse brain. Theoretical and experimental results demonstrated that changes in ? induced a dispersion of the relaxation rate constants. The fastest relaxation was achieved at ? ? 56°, where the averaged contributions from transverse components during the pulse are maximal and the contribution from longitudinal components are minimal. RAFF relaxation dispersion was compared with the relaxation dispersion achieved with off-resonance spin lock T(??) experiments. As compared with the off-resonance spin lock T(??) method, a slower rotating frame relaxation rate was observed with RAFF, which under certain experimental conditions is desirable.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1096-0856
pubmed:author
pubmed:copyrightInfo
Copyright © 2011 Elsevier Inc. All rights reserved.
pubmed:issnType
Electronic
pubmed:volume
209
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
269-76
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Relaxation dispersion in MRI induced by fictitious magnetic fields.
pubmed:affiliation
Department of Biotechnology and Molecular Medicine A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland. timo.liimatainen@uef.fi
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural