Method and system for concentrating magnetization of nuclear spins

Patent metadata

Field	Value
Publication number	US-9810758-B2
Application number	US-201314415820-A
Country	US
Kind code	B2
Filing date	Jul 23, 2013
Priority date	Jul 23, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Apparatuses and methods are provided for concentrating the magnetization of nuclear spins within a body, in one apparatus, a body having an electron spin moments and nuclear spin moments may subject to a polarizing magnetic field and a gradient magnetic field, such that a space-varied distribution of magnetic resonant frequencies of respective electron spin moments in the body is induced. The body may then be subject to a time-varying magnetic field configured to induce a spatial gradient of the electron spin magnetization such that concentrations of nuclear spin magnetization are induced. The body may be configured to receive a biological sample such that a concentration of nuclear spin magnetization may diffuse into the biological sample. The apparatus may further include a sensor configured to detect nuclear spin magnetization within the biological sample.

First claim

We claim:

1. An apparatus comprising:
a body comprising nuclear spin moments and electron spin moments within at least a portion of the body;
a magnetic device configured to provide a static magnetic field within the portion of the body, wherein the static magnetic field is configured to (a) cause a nuclear spin magnetization carried by respective pairs of the nuclear spin moments to be substantially pairwise conserved, (b) substantially align the electron spin moments with a direction of the static magnetic field, and (c) induce a space-varied distribution of magnetic resonance frequencies of respective electron spin moments; and
an alternating-field magnet configured to provide a time-varying magnetic field across the portion of the body, wherein the time-varying magnetic field is configured to induce a spatial gradient in a local magnetization of the respective electron spin moments such that concentrations of the nuclear spin magnetizations carried by respective pairs of the nuclear spin moments are spatially varied according to the spatial gradient in local magnetization of the respective electron spin moments.

2. The apparatus of claim 1 , wherein the magnetic device comprises a first magnetic subdevice and a second magnetic subdevice, wherein the first magnetic subdevice is configured to provide a first magnetic field component of the static magnetic field to (a) cause the nuclear spin magnetization carried by respective pairs of the nuclear spin moments to be substantially pairwise conserved and (b) substantially align the electron spin moments with a direction of the static magnetic field, and wherein the second magnetic subdevice is configured to provide a second magnetic field component of the static magnetic field to induce a space-varied distribution of magnetic resonance frequencies of respective electron spin moments.

3. The apparatus of claim 2 , wherein the first magnetic subdevice comprises a superconducting coil configured to produce a uniform magnetic field across the apparatus.

4. The apparatus of claim 3 , wherein the second magnetic subdevice comprises a superconductor material comprising vortices configured to modify the uniform magnetic field to induce the space-varied distribution of magnetic resonance frequencies of respective electron spin moments.

5. The apparatus of claim 1 , wherein the body comprises a substance with magnetically unpaired electrons.

6. The apparatus of claim 1 , wherein the magnetic device comprises a permanent magnet.

7. The apparatus of claim 1 , wherein the static magnetic field has a magnitude within a range of about 50 mT to about 10 T.

8. The apparatus of claim 1 , wherein the body is configured to receive a biological sample at a location on the body, and wherein the alternating-field magnet is configured to concentrate nuclear spin magnetizations at substantially the location of the biological sample on the body such that the nuclear spin magnetization within the body causes diffusion of nuclear spin magnetizations in the biological sample.

9. The apparatus of claim 8 , further comprising a sensor, wherein the sensor is configured to detect nuclear spin magnetization in the biological sample.

10. The apparatus of claim 9 , wherein the sensor is a multi-pass cell magnetometer sensor configured to detect biomagnetic signals from the biological sample in a medical imaging application.

11. The apparatus of claim 1 , wherein the alternating-field magnet comprises a radio-frequency coil, and wherein the radio frequency coil is configured to be activated by an alternating current such that the spatial gradient in local magnetizations of the electron spin moments is dependent on a frequency of the alternating current.

12. The apparatus of claim 1 , wherein the static magnetic field is configured to provide a magnetic field magnitude sufficient to cause the nuclear spin magnetization to be substantially pairwise conserved throughout the portion of the body.

13. A method comprising:
applying a static magnetic field across at least a portion of a body to (a) cause a nuclear spin magnetization carried by respective pairs of the nuclear spin moments to be substantially pairwise conserved, (b) substantially align the electron spin moments with a direction of the first magnetic field, and (c) induce a space-varied distribution of magnetic resonance frequencies of respective electron spin moments; and
activating an alternating-field magnet to provide a time-varying magnetic field across at least the portion of the body, wherein the time-varying magnetic field is configured to induce a spatial gradient in local magnetizations of the electron spin moments such that concentrations of the nuclear spin magnetizations carried by respective pairs of nuclear spin moments in at least the portion of the body are spatially variable according to the spatial gradient in local magnetization of the respective electron spin moments.

14. The method of claim 13 , wherein applying a static magnetic field across at least a portion of the body comprises:
applying a first magnetic field component of the static magnetic field to (a) cause the nuclear spin magnetization carried by respective pairs of the nuclear spin moments to be substantially pairwise conserved and (b) substantially align the electron spin moments with a direction of the static magnetic field; and
applying a second magnetic field component of the static magnetic field to induce a space-varied distribution of magnetic resonance frequencies of respective electron spin moments.

15. The method of claim 13 , wherein the alternating-field magnet comprises a radio-frequency coil, and wherein activating an alternating-field magnet to provide a time-varying magnetic field across at least the portion of the body comprises:
applying an alternating current to the radio-frequency coil, wherein the spatial gradient in local magnetizations of the electron spin moments is dependent on a frequency of the alternating current.

16. A non-transitory computer readable medium having stored thereon instructions executable by a computing device to cause the computing device to perform functions comprising:
detecting a space-varied distribution of magnetic resonance frequencies of electron spin moments in at least a portion of a body;
determining a time-varying magnetic field based on the detected space-varied distribution of magnetic resonance frequencies of electron spin moments, wherein the time-varying magnetic field is configured to induce a spatial gradient in local magnetizations of the electron spin moments such that concentrations of nuclear spin magnetizations in the body are spatially varied according to the spatial gradient in local magnetization of the respective electron spin moments; and
activating an alternating-field magnet to provide the time-varying magnetic field across at least the portion of the body.

17. The non-transitory computer readable medium of claim 16 , wherein the space-varied distribution of magnetic resonance frequencies of electron spin moments in at least the portion of the body is induced by a static magnetic field provided by a magnetic device.

18. The non-transitory computer readable medium of claim 16 , wherein a biological sample is positioned at a location on the body, and wherein activating an alternating-field magnet to provide a time-varying magnetic field across at least the portion of the body comprises:
concentrating nuclear spin magnetizations at substantially the location of the biological sample on the body such that the nuclear spin magnetizations

Assignees

• Univ Washington Through Its Center For Commercialization

Inventors

• Sidles John A
• Jacky Jon
• Garbini Joseph L
• Picone Rico

Classifications

• G01R33/543 Primary

  Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription (G01R33/546 takes precedence) · CPC title

• G01R33/383

  using permanent magnets · CPC title

• G01R33/60

  using electron paramagnetic resonance (G01R33/24, G01R33/62 take precedence) · CPC title

• G01R33/3808

  Magnet assemblies for single-sided MR wherein the magnet assembly is located on one side of a subject only; Magnet assemblies for inside-out MR, e.g. for MR in a borehole or in a blood vessel, or magnet assemblies for fringe-field MR · CPC title

• G01R33/3815

  with superconducting coils, e.g. power supply therefor · CPC title