Rachel E Martin

US Patent:

8614575, Dec 24, 2013

Filed:

Jun 16, 2006

Appl. No.:

11/917639

Inventors:

Vasiliki Demas - Oakland CA, US
Alexander Pines - Berkeley CA, US
Rachel W. Martin - Irvine CA, US
John Franck - Berkeley CA, US
Jeffrey A. Reimer - El Cerrito CA, US

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

G01V 3/00

US Classification:

324309, 324307

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 in-situ and ex-situ 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({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}(t) with i basis functions and j variables for each basis function, resulting in vvariables; c) providing a measured value Ω, which is an temporally accumulated dephasing due to the inhomogeneities of B({right arrow over (r)}); and d) minimizing a difference in the local dephasing angle φ({right arrow over (r)},t)=γ∫√{square root over (|{right arrow over (B)}({right arrow over (r)},t′)|+({right arrow over (r)}{right arrow over (G)}G(t′)+∥{right arrow over (B)}({right arrow over (r)})∥Δω({right arrow over (r)},t′)/γ))}dt′−Ω by varying the vvariables to form a set of minimized vvariables. 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.

US Patent:

20070194788, Aug 23, 2007

Filed:

Jan 19, 2007

Appl. No.:

11/625209

Inventors:

Alexander Pines - Berkeley CA, US
Daniel Topgaard - Hastveda, SE
Dimitrios Sakellariou - Boulogne Billancourt, FR
Rachel Martin - Irvine CA, US
Carlos Meriles - Fort Lee NJ, US

International Classification:

G01V 3/00

US Classification:

324307000, 324320000, 324318000

Abstract:

Methods and systems for compensating for static magnetic field inhomogeneities during nuclear magnetic resonance detection are disclosed. Application of radio frequency pulses and/or magnetic field gradients may be used to correct for spin dephasing caused by the inhomogeneities. The methods and system may be used to improve signal-to-noise ratios in NMR and MRI systems where magnetic field inhomogeneity may have an effect.