Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1987-06-02
1992-06-23
Tokar, Michael J.
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
G01R 3320
Patent
active
051246490
ABSTRACT:
A gradient magnetic field control (20) and a transmitter (30) are operated under the control of a timing and control computer (40) to generate magnetic resonance excitation pulse sequences. Each sequence provides phase encoding with one of a plurality of phase angles to the resultant resonance signals. A receiver (34) receives the phase encoded magnetic resonance signals which are digitized by an analog to digital converter (50) to form a plurality of views which are stored in a view memory (52). A larger plurality of views are generated adjacent a central or zero phase angle, e.g. views -63 to +64 of FIG. 2, and only one or a smaller plurality of views are generated adjacent peripheral phase angles, e.g. views -127 to -64 and +65 to +128 of FIG. 2. The slower, low frequency motion artifacts, such as respiratory motion artifacts, manifest themselves in the low frequency phase encoded views adjacent the zero phase encode angle. Averaging a plurality of views encoded adjacent the zero phase angle attenuates low frequency motion artifacts. The high frequency views adjacent the .+-.90.degree. phase angles contribute little or nothing to the low frequency motion artifacts. Accordingly, the high frequency views are either uniquely collected or a smaller number are averaged.
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Denison Kenneth S.
Holland G. Neil
Picker International Inc.
Tokar Michael J.
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