Linked Life Data

15862245

Source:http://linkedlifedata.com/resource/pubmed/id/15862245

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2005-5-2
pubmed:abstractText
While MRI at very low magnetic fields has certain potential advantages, it may also face problems that are not typical for MRI at conventional and high field (0.1-10T). Major differences arise due to the presence of concomitant components of inhomogeneous magnetic field (gradients) that are transverse to the major B(z) field, B(0). These concomitant transverse field components are inevitably generated by the same gradient coils that generate desired B(z) imaging gradients as routinely used in MRI for spatial encoding. In the hypothetical case (linear spatial variation of B(z) field amplitude due to the imaging gradients, no concomitant transverse field components, no B(0) and B(1) field inhomogeneities, etc.), Fourier transform MRI preserves the shape of the real object being examined. It is demonstrated herein that unavoidable concomitant transverse field gradients, G, result in an image deformation of the object's actual shape by bending straight lines and planes with a characteristic curvature radius R(c)=B(0)/G. For imaging gradients on the order of 10 mT/m and B(0) of 1T, the radius R(c) is about 100 m and image distortions are generally negligible. However, for B(0) of 1 mT, R(c) is 10 cm, which is less than a typical FOV in human studies. This manuscript derives expressions describing geometrical relationships between the imaged object and the obtained MR data. In addition to geometrical distortions, image intensity will be modulated in a complex, spatially dependent manner. Hence, if unaccounted for, corresponding image distortions-geometry and intensity-will create substantial difficulties in very low field image interpretation.
pubmed:grant
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-11543589, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-11867733, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-12111949, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-12210916, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-12762989, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-14559342, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-15029510, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-15324752, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-15690496, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-2325514, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-8028666, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-8350723, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-9469714, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-9543422, http://linkedlifedata.com/resource/pubmed/commentcorrection/15862245-9887285
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1090-7807
pubmed:author
pubmed:issnType
Print
pubmed:volume
174
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
279-86
pubmed:dateRevised
2011-9-26
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Image artifacts in very low magnetic field MRI: the role of concomitant gradients.
pubmed:affiliation
Department of Radiology, Washington University, One Brooking Drive, St. Louis, MO 63130, USA. YablonskiyD@wustl.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, N.I.H., Extramural