Document Detail


Microtesla MRI with dynamic nuclear polarization.
MedLine Citation:
PMID:  20843715     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by 2-4 orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 μT, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5-5.7 mT fields using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as large as -95 for protons and as large as -200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by low-temperature dissolution DNP.
Authors:
Vadim S Zotev; Tuba Owens; Andrei N Matlashov; Igor M Savukov; John J Gomez; Michelle A Espy
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-08-24
Journal Detail:
Title:  Journal of magnetic resonance (San Diego, Calif. : 1997)     Volume:  207     ISSN:  1096-0856     ISO Abbreviation:  J. Magn. Reson.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-18     Completed Date:  2011-02-22     Revised Date:  2011-11-01    
Medline Journal Info:
Nlm Unique ID:  9707935     Medline TA:  J Magn Reson     Country:  United States    
Other Details:
Languages:  eng     Pagination:  78-88     Citation Subset:  IM    
Copyright Information:
Published by Elsevier Inc.
Affiliation:
Los Alamos National Laboratory, Applied Modern Physics Group, MS D454, Los Alamos, NM 87545, USA. vzotev@laureateinstitute.org
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MeSH Terms
Descriptor/Qualifier:
Algorithms
Carbon Radioisotopes / chemistry
Cyclic N-Oxides / chemistry
Electromagnetic Fields
Electron Spin Resonance Spectroscopy
Free Radicals / chemistry
Magnetic Resonance Imaging / instrumentation*
Nitrogen Oxides / chemistry
Signal Processing, Computer-Assisted
Grant Support
ID/Acronym/Agency:
R01-EB006456/EB/NIBIB NIH HHS
Chemical
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Cyclic N-Oxides; 0/Free Radicals; 0/Nitrogen Oxides; 2564-83-2/TEMPO

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


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