Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1987-07-22
1989-04-18
Levy, Stewart J.
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
324309, G01R 3320
Patent
active
048230855
ABSTRACT:
Phase error contributions in pixels of a complex image of a nuclear magnetization distribution in a body region due to inhomogeneities of the steady, uniform magnetic field which are caused by the magnetic susceptibility of, for example a patient to be examined and by eddy currents are eliminated by processing the resonance signals obtained in multiple cycles of different magnetic field characteristics according to the assumption that the phase error varies smoothly as a function of the location in the complex image. A corrected phase and the corresponding phase error of a given pixel are determined and then the corrected errors of the next adjacent pixels are sequentially determined and a corrected phase 0 or .+-..pi. assigned to the respective next adjacent pixel, if the phase difference between its phase and the known phase error of the preceding pixel is modulo 2.pi. in intervals (-.DELTA.,.DELTA.), (.+-..pi.-.DELTA.,.+-..pi.+.DELTA.) representing the maximum phase error difference between the adjacent pixels, where the phase error of the next pixel is the difference between its non-corrected and its corrected phase decreased or increased by .eta.2.pi. as to be minimized with respect to the phase error of the preceding adjacent pixel. This enables elimination of the phase error by only a single scan of the body itself.
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Cuppen Johannes J. M.
Fuderer Miha
Briody Thomas A.
Haken Jack E.
Levy Stewart J.
O'Shea Kevin D.
Slobod Jack D.
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