NMR, MRI, and spectroscopic MRI in inhomogeneous fields
Abstract
A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in insitu and exsitu systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over ({right arrow over (B)}.sub.1({right arrow over (r)},t').sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.
 Inventors:
 Issue Date:
 Research Org.:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1111464
 Patent Number(s):
 8614575
 Application Number:
 11/917,639
 Assignee:
 The Regents of the University of California (Oakland, CA)
 Patent Classifications (CPCs):

G  PHYSICS G01  MEASURING G01R  MEASURING ELECTRIC VARIABLES
G  PHYSICS G01  MEASURING G01N  INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
 DOE Contract Number:
 AC0205CH11231
 Resource Type:
 Patent
 Country of Publication:
 United States
 Language:
 English
 Subject:
 47 OTHER INSTRUMENTATION
Citation Formats
Demas, Vasiliki, Pines, Alexander, Martin, Rachel W, Franck, John, and Reimer, Jeffrey A. NMR, MRI, and spectroscopic MRI in inhomogeneous fields. United States: N. p., 2013.
Web.
Demas, Vasiliki, Pines, Alexander, Martin, Rachel W, Franck, John, & Reimer, Jeffrey A. NMR, MRI, and spectroscopic MRI in inhomogeneous fields. United States.
Demas, Vasiliki, Pines, Alexander, Martin, Rachel W, Franck, John, and Reimer, Jeffrey A. Tue .
"NMR, MRI, and spectroscopic MRI in inhomogeneous fields". United States. https://www.osti.gov/servlets/purl/1111464.
@article{osti_1111464,
title = {NMR, MRI, and spectroscopic MRI in inhomogeneous fields},
author = {Demas, Vasiliki and Pines, Alexander and Martin, Rachel W and Franck, John and Reimer, Jeffrey A},
abstractNote = {A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in insitu and exsitu systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over ({right arrow over (B)}.sub.1({right arrow over (r)},t').sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2013},
month = {12}
}