Small magnet and RF coil for magnetic resonance relaxometry
First Claim
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1. A probehead for use in a portable magnetic resonance relaxometer, comprising:
- (a) two permanent magnets connected by a steel c-shaped yoke, the south pole surface of one of the permanent magnets opposing the north pole surface of the other permanent magnet to form a gap and to provide the magnetic field in the gap at a strength of less than 1.1 Tesla;
(b) a space capable of accommodating a sample volume having an associated excitable volume; and
(c) a radiofrequency coil positioned partly or completely within the gap, said radiofrequency coil wound in a cylindrical shape to enclose a volume having a diameter of approximately 1 mm and a length of approximately 2 mm, the radiofrequency coil being positioned such that its detection volume overlaps at least partly with the excitable volume;
wherein the magnetic field provided is inhomogeneous and the space accommodating the sample volume and the radiofrequency coil are adapted and positioned according to a radiofrequency CPMG pulse bandwidth optimized for a magnetic field distribution corresponding to the position of the sample volume; and
wherein the probehead is optimized to obtain T2 relaxometry parameters from a sample contained in the detection volume.
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Abstract
Small and inexpensive probeheads for use in nuclear magnetic resonance systems, in particular, magnetic resonance relaxometry systems are provided. The design of the magnet-radiofrequency coil configurations within the probeheads is guided by an excitation bandwidth associated with radiofrequency pulses to be applied to a sample.
85 Citations
14 Claims
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1. A probehead for use in a portable magnetic resonance relaxometer, comprising:
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(a) two permanent magnets connected by a steel c-shaped yoke, the south pole surface of one of the permanent magnets opposing the north pole surface of the other permanent magnet to form a gap and to provide the magnetic field in the gap at a strength of less than 1.1 Tesla; (b) a space capable of accommodating a sample volume having an associated excitable volume; and (c) a radiofrequency coil positioned partly or completely within the gap, said radiofrequency coil wound in a cylindrical shape to enclose a volume having a diameter of approximately 1 mm and a length of approximately 2 mm, the radiofrequency coil being positioned such that its detection volume overlaps at least partly with the excitable volume; wherein the magnetic field provided is inhomogeneous and the space accommodating the sample volume and the radiofrequency coil are adapted and positioned according to a radiofrequency CPMG pulse bandwidth optimized for a magnetic field distribution corresponding to the position of the sample volume; and
wherein the probehead is optimized to obtain T2 relaxometry parameters from a sample contained in the detection volume. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of preparing a probehead for use in a portable magnetic resonance relaxometer, the method comprising the steps of:
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(a) attaching two magnets or two magnetic field generators to a steel c-shaped yoke such that the south pole surface of one of the magnets or magnetic field generators opposes the north pole surface of the other magnet or magnetic field generator to form a gap between the magnets or magnetic field generators and to provide a magnetic field in the gap having a strength of less than about 1.1 Tesla; (b) positioning a space capable of accommodating a sample volume having an associated excitable volume; and (c) positioning a radiofrequency coil wound in a cylindrical shape to enclose a volume having a diameter of approximately 1 mm and a length of approximately 2 mm and being adapted to emit a radiofrequency pulse with a pulse length, the radiofrequency coil being positioned and designed to have the detection volume at least partly overlap with an excitable volume within the gap; wherein the probehead is optimized to obtain T2 relaxometry parameters from a sample contained in the sample volume.
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Specification