Magnetic resonance system and method employing a digital SQUID

• US 10,509,084 B1
• Filed: 04/07/2017
• Issued: 12/17/2019
• Est. Priority Date: 11/24/2009
• Status: Active Grant

• Current Assignee: Johnson Revocable Trust
• Original Assignee: Hypres, Inc.
• Inventors: Radparvar, Masoud, Kadin, Alan M., Track, Elie K., Hitt, Richard E.
• Primary Examiner(s): Arana, Louis M
• Application Number:
  US15/482,266
• Time in Patent Office: 984 Days
• Field of Search: 324309, 324307
• CPC Class Codes: G01R 33/323 Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR
• CPC Class Codes: G01R 33/326 involving a SQUID
• CPC Class Codes: G01R 33/3621 NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
• CPC Class Codes: G01R 33/445 MR involving a non-standard magnetic field B0, e.g. of low magnitude as in the earth's magnetic field or in nanoTesla spectroscopy, comprising a polarizing magnetic field for pre-polarisation, B0 with a temporal variation of its magnitude or direction such as field cycling of B0 or rotation of the direction of B0, or spatially inhomogeneous B0 like in fringe-field MR or in stray-field imaging
• CPC Class Codes: G01R 33/50 based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
• CPC Class Codes: G01R 33/567 gated by physiological signals , i.e. synchronization of acquired MR data with periodical motion of an object of interest, e.g. monitoring or triggering system for cardiac or respiratory gating

Abstract

A magnetic resonance system, comprising at least one SQUID, configured to receive a radio frequency electromagnetic signal, in a circuit configured to produce a pulsatile output having a minimum pulse frequency of at least 1 GHz which is analyzed in a processor with respect to a timebase, to generate a digital signal representing magnetic resonance information. The processor may comprise at least one rapid single flux quantum circuit. The magnetic resonance information may be image information. A plurality of SQUIDs may be provided, fed by a plurality of antennas in a spatial array, to provide parallel data acquisition. A broadband excitation may be provided to address a range of voxels per excitation cycle. The processor may digitally compensate for magnetic field inhomogeneities.

Claims

1. A magnetic resonance system comprising:

a plurality of antennas, each configured to concurrently receive a broadband electromagnetic signal representing magnetic resonance emissions from a volume of tissue over a range of magnetic field strengths to produce a corresponding broadband electronic signal;

a plurality of digitizers, each configured to receive and digitize the corresponding broadband electronic signal from a respective antenna at a rate of at least 1 gigasample per second to produce a broadband digitized electronic signal; and

at least one processor configured to receive the respective broadband digitized electronic signal from each of the plurality of digitizers, to perform at least one spatial processing algorithm, and to produce an output selectively dependent on a spatial characteristic of the magnetic resonance emissions from a volume of tissue over a range of magnetic field strengths.

2. The system of claim 1, wherein the received magnetic resonance signals comprise magnetic resonance emissions from hydrogen.

3. The system of claim 1, wherein the range of magnetic field strengths have a non-linear variation within the volume of tissue.

4. The system of claim 1, further comprising a magnetic field generator configured to maintain a magnetic field around the object, wherein the plurality of digitizers are magnetically shielded from the magnetic field generator.

5. The system of claim 3, wherein the range of magnetic field strengths comprises a field strength of less than about 0.4 T.

6. The system of claim 3, wherein the range of magnetic field strengths comprises a field strength of less than about 0.1 T.

7. The system of claim 1, wherein the plurality of digitizers comprise superconducting digital flux detectors.

8. The system of claim 7, wherein the superconducting digital flux detectors each comprise at least one Josephson junction configured in a circuit which functions as at least one of a superconducting quantum interference device (SQUID) and a superconducting quantum interference filter (SQIF).

9. The system of claim 1, wherein plurality of digitizers each comprise a respective superconducting flux detector configured to generate single-flux-quantum (SFQ) pulses corresponding to an amplitude of a respective magnetic field strength.

10. The system of claim 1, herein the at least one processor is further configured to produce a spatial representation of magnetic resonance properties of the tissue.

11. The system of claim 1, wherein at least one respective antenna comprises a magnetic gradiometer.

12. The system of claim 1, wherein the at least one processor is configured to produce an output representing a spatial characteristic of the magnetic resonance emissions from a plane of tissue.

13. The system of claim 1, wherein the at least one processor is configured to digitally compensate for an inhomogeneous magnetic field within the range of magnetic field strengths.

14. A magnetic resonance method comprising:

concurrently receiving a plurality of broadband electromagnetic signals, representing magnetic resonance emissions from a volume over a range of magnetic field strengths, to produce a corresponding plurality of broadband electronic signals;

concurrently digitizing the plurality of broadband electronic signals, without downconversion, to produce a plurality of digitized broadband electronic signals; and

perform at least one spatial processing algorithm on the concurrently digitized plurality of broadband electronic signals to produce an output selectively dependent on a spatial characteristic of the magnetic resonance emissions from a volume of tissue over a range of magnetic field strengths.

15. The method according to claim 14, wherein the plurality of digitized broadband electronic signals each have a respective sampling rate in excess of 1 gigasample per second.

16. The method of claim 14, further comprising:

generating a dynamically changing magnetic field in the volume that varies over time and space, and

producing a spatial image representing magnetic resonance properties of the volume.

17. The method of claim 15, wherein the plurality of broadband electronic signals are each digitized with a digitizer comprising at least one superconducting digital flux detector which functions as at least one of a superconducting quantum interference device (SQUID) and a superconducting quantum interference filter (SQIF).

18. The method according to claim 14, wherein a magnetic field within the volume is inhomogeneous, further comprising digitally compensating for the inhomogeneous magnetic field to produce an spatial image comprising a set of voxels having characteristics corresponding to a respective spatial region within the volume.

19. A magnetic resonance imaging system comprising:

a plurality of antennas each configured to receive magnetic resonance emissions from a volume having an inhomogeneous magnetic field and at least one non-linear variation of the inhomogeneous magnetic field;

a plurality of digitizers, each configured to produce a datastream corresponding to the magnetic resonance emissions from the volume at a sampling rate of at least 1 gigasample per second;

a magnetic field generator configured to alter the inhomogeneous magnetic field and at least one non-linear variation of the inhomogeneous magnetic field over time; and

at least one processor configured to;

control the magnetic field generator,

compensate for the inhomogeneous magnetic field and at least one non-linear variation of the inhomogeneous magnetic field, and

perform a spatial processing algorithm to convert the respective datastream from the plurality of digitizers into spatial data; and

at least one memory configured to store the spatial data.

20. The magnetic resonance imaging system of claim 19, wherein the antennas each comprise a gradiometer, and the plurality of digitizers each comprise at least one Josephson junction.