Magnetic resonance system and method employing a digital SQUID

• US 9,261,573 B1
• Filed: 11/25/2013
• Issued: 02/16/2016
• 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:
  US14/088,591
• Time in Patent Office: 813 Days
• Field of Search: 324/322, 324/318, 324/314
• US Class Current: 1/1
• 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 imaging system comprising:

at least one magnetic flux antenna configured to transduce a radio-frequency magnetic flux from an object under examination to an electronic signal;

at least one digital flux detector configured to sample the electronic signal from the at least one magnetic flux antenna at a rate of at least 1 giga-samples per second to produce a sampled digital datastream; and

at least one image processor configured to receive the sampled digital datastream and to produce an image representation thereof.

2. The imaging system of claim 1, wherein the radio frequency magnetic flux comprises a frequency component of at least 100 kHz represented in the sampled digital datastream.

3. The imaging system of claim 1, further comprising a magnetic field generator configured to produce a static magnetic field of less than about 0.4 T proximate to the object under examination.

4. The imaging system of claim 1, wherein the at least one digital flux detector comprises a superconducting component having a critical temperature below 20K.

5. The imaging system of claim 1, wherein the at least one digital flux detector comprises a superconducting component having a critical temperature above 20K.

6. The imaging system of claim 1, wherein the at least one digital flux detector comprises 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).

7. The imaging system of claim 1, wherein the at least one digital flux detector comprises a device configured to generate and process single-flux-quantum (SFQ) pulses.

8. The imaging system of claim 1, wherein the at least one digital flux detector comprises a superconducting multi-chip module.

9. The imaging system of claim 1, wherein the at least one digital flux detector comprises a superconducting analog-to-digital converter (ADC).

10. The imaging system of claim 1, wherein the magnetic flux antenna comprises at least one superconducting component.

11. The imaging system of claim 1, further comprising a dynamic magnetic field generator configured to generate a magnetic field proximate to the object under examination that varies over time and space.

12. The imaging system of claim 1, further comprising a closed-cycle cryocooler configured to cool at least one of the:

at least one magnetic flux antenna, and the at least one digital flux detector, to a temperature of less than about 200 K.

13. The imaging system of claim 1, comprising a plurality of magnetic flux antennas arranged in an array and a plurality of digital flux detectors.

14. The imaging system of claim 1, further comprising a magnetic field generator configured to generate a magnetic field within the object under examination, wherein the digital flux detector comprises at least one Josephson junction, is proximate to the object under examination, and is magnetically shielded from the magnetic field.

15. A magnetic resonance imaging method comprising:

transducing a radio-frequency magnetic flux from an object under examination to at least one magnetic flux antenna to generate an electronic signal;

sampling the electronic signal received from the at least one magnetic flux antenna at a rate of at least 1 giga-samples per second with at least one digital flux detector to produce a sampled digital datastream; and

processing the sampled digital datastream to produce at least image information.

16. The imaging method of claim 15, wherein the radio frequency magnetic flux comprises a frequency component of at least 100 kHz represented in the sampled digital datastream.

17. The imaging method of claim 15, wherein the at least one digital flux detector comprises a superconducting component having at least one Josephson junction.

18. The imaging method of claim 15, further comprising generating a dynamic magnetic field proximate to the object under examination that varies over time and space superposed on a static magnetic field.

19. A magnetic resonance imaging system comprising:

a plurality of magnetic flux antennas configured to transduce a radio-frequency magnetic flux from an object under examination to an electronic signal;

at least one digital flux detector configured to sample the electronic signals received from the plurality of magnetic flux antennas, each electronic signal being sampled at a rate of at least 1 giga-samples per second to produce at least one sampled digital datastream;

a magnetic field generator configured to generate a time-varying magnetic field which varies in time and space within at least a portion of the object under examination;

at least one processor configured to control the magnetic field generator, and to receive and process the at least one sampled digital datastream to calculate at least one mathematical transform and produce image information; and

at least one memory configured to store the image information,

wherein the at least one digital flux detector comprises a superconductor which is proximate to the magnetic field generator and magnetically shielded from the time-varying magnetic field.

20. The imaging system of claim 19, wherein the radio frequency magnetic flux comprises a frequency component of at least 100 kHz corresponding to a nuclear magnetic resonance of at least one type of atom in the object under examination, represented in the at least one sampled digital datastream.