Document Detail


High-field MRI of brain cortical substructure based on signal phase.
MedLine Citation:
PMID:  17586684     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The ability to detect brain anatomy and pathophysiology with MRI is limited by the contrast-to-noise ratio (CNR), which depends on the contrast mechanism used and the spatial resolution. In this work, we show that in MRI of the human brain, large improvements in contrast to noise in high-resolution images are possible by exploiting the MRI signal phase at high magnetic field strength. Using gradient-echo MRI at 7.0 tesla and a multichannel detector, a nominal voxel size of 0.24 x 0.24 x 1.0 mm3 (58 nl) was achieved. At this resolution, a strong phase contrast was observed both between as well as within gray matter (GM) and white matter (WM). In gradient-echo phase images obtained on normal volunteers at this high resolution, the CNR between GM and WM ranged from 3:1 to 20:1 over the cortex. This CNR is an almost 10-fold improvement over conventional MRI techniques that do not use image phase, and it is an approximately 100-fold improvement when including the gains in resolution from high-field and multichannel detection. Within WM, phase contrast appeared to be associated with the major fiber bundles, whereas contrast within GM was suggestive of the underlying layer structure. The observed phase contrast is attributed to local variations in magnetic susceptibility, which, at least in part, appeared to originate from iron stores. The ability to detect cortical substructure from MRI phase contrast at high field is expected to greatly enhance the study of human brain anatomy in vivo.
Authors:
Jeff H Duyn; Peter van Gelderen; Tie-Qiang Li; Jacco A de Zwart; Alan P Koretsky; Masaki Fukunaga
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Publication Detail:
Type:  Journal Article     Date:  2007-06-22
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  104     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2007 Jul 
Date Detail:
Created Date:  2007-07-11     Completed Date:  2007-09-27     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11796-801     Citation Subset:  IM    
Affiliation:
Laboratory for Advanced MRI, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room B1D-728, Bethesda, MD 20892-1065, USA. jhd@helix.nih.gov
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MeSH Terms
Descriptor/Qualifier:
Adult
Cerebral Cortex / anatomy & histology*,  chemistry,  physiology*
Echo-Planar Imaging / methods*
Female
Humans
Iron / metabolism
Male
Middle Aged
Myelin Sheath / metabolism
Grant Support
ID/Acronym/Agency:
Z01 NS002989-08/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
7439-89-6/Iron
Comments/Corrections
Comment In:
Proc Natl Acad Sci U S A. 2007 Jul 10;104(28):11513-4   [PMID:  17609374 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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