Small scale NMR spectroscopic apparatus and method
First Claim
1. A magnet assembly for providing a substantially homogeneous magnetic field within a test region for an NMR apparatus, comprising:
- a) a pair of opposed permanent magnets, each magnet having a back surface, a front surface facing the opposing permanent magnet front surface and one or more side surfaces between the front and back surfaces;
b) a pair of opposed pole cap members, each pole cap member having a back surface adjacent the front surface of one of the permanent magnets and having a front surface defining at least in part the test region between the pole cap members and facing the opposing pole cap member front surface and each pole cap member having a radially tapered side surface extending from the back surface toward the front surface, of the pole cap member of the pole cap member,c) a plurality of annular canceling magnets, the canceling magnets encircling the side surfaces of the permanent magnets and the pole cap members, and being radially polarized; and
d) a pair of opposed annular ring shims, each annular ring shim encircling at least in part the side surface of a pole cap member adjacent the front surface of the pole cap member, each annular ring shim having a length from a front surface to a back surface of the ring shim which is less than a length of the pole cap member from the front surface to the back surface of the pole cap member.
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Accused Products
Abstract
A magnet assembly for a small scale NMR spectroscopy apparatus suitable for laboratory or home use, generally comprising two permanent magnets facing one another so that the facing surfaces have opposite polarities, a pole cap on each of the two facing surfaces of the permanent magnets, and a plurality of radially polarized canceling magnets disposed about the permanent magnets and pole caps. The design and position of the radially polarized canceling magnets about the tapered pole caps reduces leakage of the magnetic field, to maintain the magnetic field strength and homogeneity within the test region, without a disadvantageous increase in the size, weight and cost of the NMR apparatus. A curved edge ring shim may be used to increase magnetic field homogeneity in the test region. Also provided is a method for measurement of glucose concentration in a fluid using NMR spectroscopy. In one aspect of the invention the fluid is a patient'"'"'s body fluid and the invention provides for in vivo measurement of the glucose concentration. The method comprises spectral editing in which a RF pulse sequence is used to isolate desired resonances of glucose and thereby facilitate resolution of the glucose signal.
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Citations
29 Claims
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1. A magnet assembly for providing a substantially homogeneous magnetic field within a test region for an NMR apparatus, comprising:
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a) a pair of opposed permanent magnets, each magnet having a back surface, a front surface facing the opposing permanent magnet front surface and one or more side surfaces between the front and back surfaces; b) a pair of opposed pole cap members, each pole cap member having a back surface adjacent the front surface of one of the permanent magnets and having a front surface defining at least in part the test region between the pole cap members and facing the opposing pole cap member front surface and each pole cap member having a radially tapered side surface extending from the back surface toward the front surface, of the pole cap member of the pole cap member, c) a plurality of annular canceling magnets, the canceling magnets encircling the side surfaces of the permanent magnets and the pole cap members, and being radially polarized; and d) a pair of opposed annular ring shims, each annular ring shim encircling at least in part the side surface of a pole cap member adjacent the front surface of the pole cap member, each annular ring shim having a length from a front surface to a back surface of the ring shim which is less than a length of the pole cap member from the front surface to the back surface of the pole cap member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A magnet assembly for providing a substantially homogeneous magnetic field within a test region for an NMR apparatus, comprising:
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a) a pair of opposed permanent magnets, each magnet having a back surface, a front surface facing the opposing permanent magnet front surface and a side surface extending between the back and front surfaces; b) a pair of opposed pole cap members, each pole cap member having a back surface adjacent the front surface of one of the permanent magnets and a front surface that defines at least in part a test region between the pole cap members that faces the opposing pole cap member front surface, and each pole cap member having radially tapered side surfaces extending from the back surface of the pole cap member toward the front surface of the pole cap member; and c) a plurality of annular canceling magnets encircling the side surface of the pole cap member, which are adjacent to and longitudinally displaced from one another, and at least one annular canceling magnet encircling the side surfaces of the pole cap member and the permanent magnet at a junction therebetween, which has a height from an inner surface to an outer surface greater than a height of the canceling magnets encircling the pole cap member, and at least one annular canceling magnet encircling the side surface of the permanent magnet which has a height from an inner surface to an outer surface less than the height of the canceling magnets encircling around the pole cap member.
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29. A NMR apparatus for measurement of a constituent concentration in a patient, comprising:
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a) a magnet assembly for providing a substantially homogeneous magnetic field within a test region, comprising a pair of opposed permanent magnets, each magnet having a back surface, a front surface facing the opposing permanent magnet front surface and one or more side surfaces disposed between the front and back surfaces; a pair of opposed pole cap members, each pole cap member having a back surface adjacent the front surface of one of the permanent magnets, a front surface facing the opposing pole cap member front surface, and a radially tapered side surface extending from the back surface of the pole cap member toward the front surface of the pole cap member; and a plurality of annular canceling magnets encircling the side surfaces of the permanent magnets and pole cap members and being radially polarized; b) a pair of opposed annular ring shims, each annular ring shim encircling at least in part the side surface of a pole cap member adjacent the front surface of the pole cap member, each annular ring shim having a length from a front surface to a back surface of the ring shim which is less than a length of the pole cap member from the front surface to the back surface of the pole cap member; c) a coil; and d) a test region defined at least in part by said pole caps and said coil.
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Specification