Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Patent
1986-08-15
1987-12-29
Tokar, Michael J.
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
324306, G01R 3320
Patent
active
047163674
ABSTRACT:
The present invention provides an NMR image in which the individual image element intensities are proportional to the amount of nuclei flowing within a window of velocities. The invention is predicated on the fact that static nuclei in a static reference frame provide the most intense portions of the NMR signal. A moving reference frame for image creation is created moving at the velocity of the nuclei to be imaged. Nuclei moving at the same velocity as the reference frame thus have zero velocity with respect to the reference frame, and hence provide maximum signal intensity. In the described embodiment, the moving reference frame is created by satisfaction of two conditions, which relate to tracking the Larmor frequency and phase of the nuclei of interest moving in a gradient. These conditions may be satisfied by variation of the main NMR magnetic field H.sub.o as a function of time. The field may be varied simply by addition of an additional coil to conventional NMR equipment. The invention is applicable to image formation using either steady state free precession techniques or conventional spin echo techniques.
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Brigham & Women's Hospital
Tokar Michael J.
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