Noise suppression methods and apparatus

Patent metadata

Field	Value
Publication number	US-9625543-B2
Application number	US-201615049596-A
Country	US
Kind code	B2
Filing date	Feb 22, 2016
Priority date	Sep 5, 2014
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

According to some aspects, a method of suppressing noise in an environment of a magnetic resonance imaging system is provided. The method comprising estimating a transfer function based on multiple calibration measurements obtained from the environment by at least one primary coil and at least one auxiliary sensor, respectively, estimating noise present in a magnetic resonance signal received by the at least one primary coil based at least in part on the transfer function, and suppressing noise in the magnetic resonance signal using the noise estimate.

First claim

What is claimed is:

1. A method of suppressing noise in an environment of a magnetic resonance imaging system, the method comprising:
using at least one primary coil and at least one auxiliary sensor different from the at least one primary coil to obtain multiple calibration measurements comprising a first plurality of calibration measurements obtained by the at least one auxiliary sensor and a corresponding second plurality of calibration measurements obtained by the at least one primary coil;
estimating, based on the multiple calibration measurements, a transfer function that, when applied to noise received by the at least one auxiliary sensor, provides an estimate of noise received by the at least one primary coil; and
after estimating the transfer function:
receiving a magnetic resonance signal using the at least one primary coil;
receiving a noise signal using the at least one auxiliary sensor;
estimating noise present in the magnetic resonance signal received by the at least one primary coil by applying the transfer function to the noise signal received by the at least one auxiliary sensor to obtain a noise estimate; and
suppressing noise in the magnetic resonance signal using the noise estimate.

2. The method of claim 1 , wherein the at least one primary coil is arranged within a field of view of a magnetic resonance imaging system to detect magnetic resonance signals produced by a sample when positioned within the field of view, and wherein the at least one auxiliary sensor comprises at least one auxiliary coil arranged outside the field of view.

3. The method of claim 2 , wherein the at least one auxiliary coil comprises a plurality of auxiliary coils, and wherein the first a plurality of calibration measurements is obtained from the environment using the plurality of auxiliary coils.

4. The method of claim 3 , wherein each of the plurality of auxiliary coils is positioned at a different respective location.

5. The method of claim 3 , wherein at least one of the plurality of auxiliary coils is of a different type than at least one other auxiliary coil.

6. The method of claim 3 , wherein estimating the noise present in the magnetic resonance signal comprises applying the transfer function to noise signals received by each of the plurality of auxiliary coils and obtained substantially at a same time as the at least one primary coil receives the magnetic resonance signal.

7. The method of claim 1 , wherein the noise signal is received by the at least one auxiliary coil concurrently with the at least one primary coil receiving the magnetic resonance signal.

8. The method of claim 1 , wherein each of the first plurality of calibration measurements is obtained substantially at a same time as a respective one of the second plurality of calibration measurements.

9. The method of claim 1 , wherein estimating the transfer function includes estimating the transfer function for each of a plurality of frequency bins across a spectrum of interest.

10. The method of claim 1 , wherein the at least one auxiliary sensor includes a sensor coupled to a power line to suppress environmental noise produced by the power line.

11. The method of claim 1 , wherein the magnetic resonance system is a low-field magnetic resonance imaging system.

12. The method of claim 11 , wherein the low-field magnetic resonance imaging system is configured to generate a B0 field of approximately 0.2 T or less.

13. The method of claim 11 , wherein the low-field magnetic resonance imaging system is configured to generate a B0 field of approximately 0.1 T or less.

14. The method of claim 11 , wherein the low-field magnetic resonance imaging system is configured to generate a B0 field of approximately 20 mT or less.

15. A magnetic resonance imaging (MRI) system comprising:
at least one primary coil;
at least one auxiliary sensor different from the at least one primary coil; and
at least one controller configured to:
cause the at least one primary coil and the at least one auxiliary sensor to obtain a first plurality of calibration measurements and a second plurality of calibration measurements, respectively, from an environment of the magnetic resonance imaging system;
estimate, based on the first plurality of calibration measurements and the second plurality of calibration measurements, a transfer function that, when applied to noise received by the at least one auxiliary sensor, provides an estimate of noise received by the at least one primary coil; and
after estimating the transfer function:
cause the at least one primary coil to receive a magnetic resonance signal;
cause the at least one auxiliary sensor to receive a noise signal;
estimate noise present in the magnetic resonance signal received by the at least one primary coil by applying the transfer function to the noise signal received by the at least one auxiliary sensor to obtain a noise estimate; and
suppress noise in the magnetic resonance signal using the noise estimate.

16. The MRI system of claim 15 , wherein the at least one primary coil is arranged within a field of view of the MRI system to detect magnetic resonance signals produced by a sample when positioned within the field of view, and wherein the at least one auxiliary sensor comprises at least one auxiliary coil arranged outside the field of view.

17. The MRI system of claim 16 , wherein each of the first plurality of calibration measurements is caused to be obtained substantially at a same time as a respective one of the second plurality of calibration measurements.

18. The MRI system of claim 15 , wherein the at least one controller causes the at least one auxiliary coil to receive the noise signal and the at least one primary coil to receive the magnetic resonance signal at substantially a same time.

19. The MRI system of claim 15 , wherein the at least one auxiliary sensor comprises a plurality of auxiliary coils, and wherein the first plurality of calibration measurements is obtained from the environment by using the plurality of auxiliary coils.

20. The MRI system of claim 19 , wherein each of the plurality of auxiliary coils is positioned at a different respective location.

21. The MRI system of claim 19 , wherein at least one of the plurality of auxiliary coils is of a different type than at least one other auxiliary coil.

22. The MRI system of claim 19 , wherein estimating the noise present in the magnetic resonance signal comprises applying the transfer function to noise signals obtained from the plurality of auxiliary coils substantially at a same time as the at least one primary coil receives the magnetic resonance signal.

23. The MRI system of claim 15 , wherein the at least one controller is configured to estimate the transfer function for each of a plurality of frequency bins across a spectrum of interest.

24. The MRI system of claim 15 , wherein the at least one auxiliary sensor includes a sensor coupled to a power line to suppress environmental noise produced by the power line.

25. The MRI system of claim 15 , wherein the at least one auxiliary sensor includes at least one auxiliary radio frequency coil.

26. A method of suppressing noise in an environment of a magnetic resonance imaging system, the method comprising:
using at least one primary coil and at least one auxiliary sensor different from the at least one primary coil to obtain multiple calibration measurements comprising

Assignees

• Hyperfine Res Inc

Inventors

• Rearick Todd
• Charvat Gregory L
• Rosen Matthew Scot
• Rothberg Jonathan M

Classifications

• G01R33/3858

  Manufacture and installation of gradient coils, means for providing mechanical support to parts of the gradient-coil assembly (manufacture of inductances or coils in general H01F41/00) · CPC title

• G01R33/3802 Primary

  Manufacture or installation of magnet assemblies; Additional hardware for transportation or installation of the magnet assembly or for providing mechanical support to components of the magnet assembly · CPC title

• G01R33/36

  Electrical details, e.g. matching or coupling of the coil to the receiver · CPC title

• G01R33/445 Primary

  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 title

• G01R33/3804 Primary

  Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly · CPC title