NMR machine with low field and dynamic polarization
AssigneeGeneral Electric CGR S.A.
InventorPatrick Le Roux
Life of this patent
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Abstract
Problems of homogeneity of the resonant field of an NMR machine are solved by differentiating the polarization and resonance functions assigned to coils of the field of said machine. In order to produce a magnetization, use is made of a polarization coil which produces a high field. This polarization field does not need to be homogeneous. Before making measurements, during sequences of excitation-measurement of the electromagnetic wave within the body under examination, the polarization field is switched in order to be cancelled and the body is subjected to a resonance field. This resonance field can be of much lower strength but is on the other hand much more homogeneous. By thus making use of switching of the orienting field, it is shown that the signal-to-noise ratio of the detected signal is maintained.
Claims26
An NMR machine comprising
- means for subjecting a body to be scanned to an intense magnetic polarisation field,
- means for exciting said body with an electromagnetic wave,
- means for measuring an electromagnetic wave re-emitted in response by the body, wherein said machine comprises in addition
- means for producing a resonance field of distinctly lower strength than, and orthogonal to the polarisation field,
- and means for cancelling the polarisation field prior to measurement of the electromagnetic wave, including means for damping the cancellation.
An NMR machine comprising:
- a. means for subjecting a body to be scanned to an intense magnetic polarisation field;
- b. means for exciting said body with an electromagnetic wave;
- c. means for measuring an electromagnetic wave re-emitted in response by the body;
- wherein said machine comprises in addition:
- d. means for producing a resonance field of distinctly lower strength than, and orthogonal to, the polarisation field;
- e. and means for canceling the polarisation field prior to measurement of the electromagnetic wave, including means for damping the cancellation;
- and wherein said machine is an imaging machine for carrying out a series of sequences for excitation-measurement of the electromagnetic wave and wherein said machine comprises means for periodically reestablishing the polarisation field.
An NMR machine comprising:
- a. means for subjecting a body to be scanned to an intense magnetic polarisation field;
- b. means for exciting said body with an electromagnetic wave;
- c. means for measuring an electromagnetic wave re-emitted in response by the body;
- wherein said machine comprises in addition:
- d. means for producing a resonance field of distinctly lower strength than, and orthogonal to, the polarisation field;
- e. and means for cancelling the polarisation field prior to measurement of the electromagnetic wave, including means for damping the cancellation;
- and wherein said machine comprises means for cancelling the polarisation field prior to excitation.
An NMR machine comprising
- means for subjecting a body to be scanned to an intense magnetic polarisation field,
- means for exciting said body with an electromagnetic wave,
- means for measuring an electromagnetic wave re-emitted in response by the body,
- means for producing a resonance field of distinctly lower strength than the polarisation field,
- means for cancelling the polarisation field prior to excitation of the electromagnetic wave wherein said machine comprises in addition
- means for producing a polarisation field at right angles to the resonance field,
- said means for cancelling the polarisation field comprising means for damping the cancellation.
Dependencies are inferred from the claim text.