| The contribution of chemical exchange to MRI frequency shifts in brain tissue. | |
| | |
MedLine Citation:
|
PMID: 20928888 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Recent high-field MRI studies based on resonance frequency contrast have revealed brain structure with unprecedented detail. Although subtle magnetic susceptibility variations caused by iron and myelin seem to be important to this contrast, recent research on protein solutions suggests that chemical exchange between water and macromolecular protons may contribute substantially to the observed gray-white matter frequency contrast. To investigate this, we performed spectroscopic MRI experiments at 14 T on samples of fixed human visual cortex and fresh pig brain. To allow direct observation of any exchange-induced frequency shifts, these samples were soaked in reference chemicals (TSP and dioxane) that are assumed not to be involved in exchange. For both fresh and fixed tissues and with both reference chemicals, substantial negative exchange-induced gray-white matter frequency contrast (-6.3 to -13.5 ppb) was found, whereas intracortical contrast was negligible. The sign of the gray-white matter exchange-induced frequency difference was opposite to the overall gray-white matter frequency difference observed in vivo. This suggests that exchange contributes to, but is not sufficient to explain, the frequency contrast in vivo and tissue susceptibility differences may have a greater contribution than previously thought. The exchange-dependent contribution may report on tissue chemical composition and pH. |
| | |
Authors:
|
Karin Shmueli; Stephen J Dodd; Tie-Qiang Li; Jeff H Duyn |
Related Documents
:
|
9292258 - Decreased contrast sensitivity in normal tension glaucoma determined by pattern visuall... 19375448 - Global contour shapes are coded differently from their local components. 22426708 - Which factors prognosticate spinal instability following lumbar laminectomy? 2926528 - Global spatiochromatic mechanism accounting for luminance variations in contrast sensit... 20111288 - Ultrahigh speed photography of picosecond light pulses and echoes. 19735198 - Pulsed light inactivation of listeria monocytogenes through different plastic films. |
Publication Detail:
|
Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, N.I.H., Intramural |
Journal Detail:
|
Title: Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine Volume: 65 ISSN: 1522-2594 ISO Abbreviation: Magn Reson Med Publication Date: 2011 Jan |
Date Detail:
|
Created Date: 2010-12-20 Completed Date: 2011-04-14 Revised Date: 2012-01-04 |
Medline Journal Info:
|
Nlm Unique ID: 8505245 Medline TA: Magn Reson Med Country: United States |
Other Details:
|
Languages: eng Pagination: 35-43 Citation Subset: IM |
Copyright Information:
|
© 2010 Wiley-Liss, Inc. |
Affiliation:
|
Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA. shmuelik@mail.nih.gov |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Aged Animals Dioxanes / chemistry* Female Humans Image Interpretation, Computer-Assisted / methods* Magnetic Resonance Imaging / methods* Phosphates / chemistry* Reproducibility of Results Sensitivity and Specificity Swine Visual Cortex / anatomy & histology*, chemistry* |
| Grant Support | |
ID/Acronym/Agency:
|
Z99 NS999999/NS/NINDS NIH HHS |
| Chemical | |
Reg. No./Substance:
|
0/Dioxanes; 0/Phosphates; 123-91-1/1,4-dioxane; 7632-05-5/sodium phosphate |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Growth hormone mediates pubertal skeletal development independent of hepatic IGF-1 production.
Next Document: The effect of blood inflow and B(1)-field inhomogeneity on measurement of the arterial input functio...