Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1997-11-19
2000-05-23
Oda, Christine K.
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
324307, 600410, G01V 300
Patent
active
060669497
ABSTRACT:
Disclosed is a method for characterizing the gradient subsystem of a Magnetic Resonance (MR) system. The method uses a Fourier-transform analysis to directly measure the k-space trajectory produced by an arbitrary gradient waveform. In addition, the method can be easily extended to multiple dimensions, and can be adapted to measuring residual gradient effects such as eddy currents. Several examples of gradient waveform and eddy-current measurements are presented. Also, it is demonstrated how the eddy-current measurements are presented. Also, it is demonstrated how the eddy-current measurements can be parameterized with an impulse-response formalism for later use in system tuning. When compared to a peak-fitting analysis, this technique provides a more direct extraction of the k-space measurements, which reduces the possibility of analysis error. This approach also has several advantages as compared to the conventional eddy-current measurement technique, including the ability to measure very short time constant effects.
REFERENCES:
patent: 4698591 (1987-10-01), Glover et al.
patent: 4950994 (1990-08-01), Glover et al.
Nikolaos G. Papdakis et al., "A General Method for Measurement of the Time Integral of Variant Magnetic Field Gradients: Application to 2D Spiral Imaging", Magnetic Resonance Imaging, vol. 15, No. 5, pp. 567-578, (1997).
A. A. Wilkinson et al., "Spatially Resolved Measurement of Induced Time-Variant Magnetic Fields in 1, 2, or 3 Dimensions: Application to 2D k-space Trajectory Determination", Procedings of the ISMRM 4th Annual Meeting, New York, p. 1490, (1996).
Alley Marcus T.
Pelc Norbert J.
Oda Christine K.
Shrivastav Brij B.
The Board of Trustees of the Leland Stanford Junior University
Woodward Henry K.
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