Nuclear magnetic resonance systems
AssigneePicker International, Inc.
InventorsIan R. Young, Colin G. Harrison
Life of this patent
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Abstract
The invention concerns the production of gradient fields for nuclear magnetic resonance apparatus particularly imaging apparatus. It has been earlier proposed that samples of the resonance signal be taken at intervals such that the field gradient integrals in each such interval are the same. This sampling is at unequal time intervals. It is now proposed to provide the gradient fields in discrete pulses with spaces in between at which samples can be taken. It is then straightforward to make the pulses of equal field integral or to provide an extra small pulse in one or both of the orthogonal gradients if the field integral should need adjusting before the next sample.
Claims10
A method of examining a body by nuclear magnetic resonance, including:
- applying magnetic fields to induce resonance preferentially in a slice of the body;
- subsequently applying at least one further magnetic field having a gradient in a chosen direction in the slice to induce a dispersion of the resonance frequencies in said chosen direction in the slice;
- and measuring resonance signals from the slice at intervals during the applications of the field gradient, the total field integral of the gradient component being substantially equal between successive samples;
- wherein the field gradient is applied as a sequence of discrete pulses with intervals of substantially zero field gradient intensity between adjacent pulses, and the resonance signals are sampled during at least some of the said intervals.
An apparatus for examining a body by nuclear magnetic resonance, the apparatus comprising means for preferentially inducing resonance in nuclei in a slice of the body;
- means for applying a plurality of pulses of a magnetic field having a gradient in a chosen direction in the slice to include a dispersion of the resonance frequencies in said chosen direction, and with intervals of substantially zero field gradient intensity between adjacent pulses;
- and means for measuring resonance signals from said nuclei in at least some of said intervals such that the total field integral of the said field is substantially equal between successive measurements.
Dependencies are inferred from the claim text.