Gradient waveform design for low-field magnetic resonance imaging systems

Patent metadata

Field	Value
Publication number	US-11422216-B2
Application number	US-202117210374-A
Country	US
Kind code	B2
Filing date	Mar 23, 2021
Priority date	Mar 24, 2020
Publication date	Aug 23, 2022
Grant date	Aug 23, 2022

Abstract

Systems and methods for generating a gradient waveform for use by a low-field MRI system to generate a gradient magnetic field are provided herein. The gradient waveform can be determined using first information indicative of the gradient waveform and second information indicative of hardware constraints of the low-field MRI system including a maximum voltage of the gradient power amplifier, a maximum slew rate of the gradient coil, a resistance of the gradient coil, and an inductance of the gradient coil. In some embodiments, the gradient waveform can be a trapezoidal gradient waveform determined to have a non-linear ramp-up portion and/or a non-linear ramp-down portion.

First claim

What is claimed is:

1. A method of generating a gradient waveform for use by a low-field magnetic resonance imaging (MRI) system to generate a gradient magnetic field, the low-field MRI system comprising a gradient coil and a gradient power amplifier for driving the gradient coil, the method comprising:
accessing first information indicative of the gradient waveform;
accessing second information indicative of hardware constraints of the low-field MRI system;
determining the gradient waveform using the first information and the second information, wherein the gradient waveform is a trapezoidal gradient waveform having a non-linear ramp-up portion and/or a non-linear ramp-down portion; and
generating the gradient waveform.

2. The method of claim 1 , further comprising generating the gradient magnetic field by using the gradient power amplifier and the gradient waveform to drive the gradient coil.

3. The method of claim 1 , wherein determining the gradient waveform comprises determining a shape of the ramp-up portion and/or the ramp-down portion using the first information and the second information.

4. The method of claim 1 , wherein determining the gradient waveform comprises determining gradient waveform parameters subject to hardware constraints specified using a differential equation, the differential equation specified in part using the second information.

5. The method of claim 1 , wherein accessing the first information comprises accessing information including a moment of the gradient magnetic field, a duration of the gradient magnetic field, and/or a maximum value of the gradient magnetic field.

6. The method of claim 1 , wherein accessing the first information comprises accessing a pre-determined gradient waveform.

7. The method of claim 1 , wherein accessing the second information comprises accessing information indicative of a maximum voltage of the gradient power amplifier, a maximum slew rate of the gradient coil, a resistance of the gradient coil, and an inductance of the gradient coil.

8. The method of claim 7 , wherein the maximum slew rate has a magnitude in a range from 10 T/m/s to 80 T/m/s.

9. The method of claim 7 , wherein the maximum slew rate has a magnitude in a range from 25 T/m/s to 65 T/m/s.

10. The method of claim 7 , wherein the maximum voltage of the gradient power amplifier has a magnitude in a range from 20 V to 120 V.

11. The method of claim 7 , wherein the maximum voltage of the gradient power amplifier has a magnitude in a range from 40 V to 60 V.

12. The method of claim 1 , further comprising:
after determining the gradient waveform, rotating a frame of reference of the gradient waveform to match a frame of reference of the low-field MRI system.

13. The method of claim 1 , wherein the low-field MRI system further comprises at least one permanent magnet configured to generate a B 0 magnetic field having a strength less than 0.2 T.

14. The method of claim 1 , wherein the low-field MRI system further comprises at least one permanent magnet configured to generate a B 0 magnetic field having a strength in a range from 50 mT to 0.1 T.

15. At least one non-transitory computer-readable storage medium storing processor-executable instructions that, when executed by a low-field magnetic resonance imaging (MRI) system, cause the low-field MRI system to perform a method of generating a gradient waveform for use by the low-field MRI system to generate a gradient magnetic field, the low-field MRI system comprising a gradient coil and a gradient power amplifier for driving the gradient coil, the method comprising:
accessing first information indicative of the gradient waveform;
accessing second information indicative of hardware constraints of the low-field MRI system;
determining the gradient waveform using the first information and the second information, wherein the gradient waveform is a trapezoidal gradient waveform having a non-linear ramp-up portion and/or a non-linear ramp-down portion; and
generating the gradient waveform.

16. The at least one non-transitory computer-readable storage medium of claim 15 , wherein determining the gradient waveform comprises determining a shape of the ramp-up portion and/or the ramp-down portion using the first information and the second information.

17. The at least one non-transitory computer-readable storage medium of claim 15 , wherein determining the gradient waveform comprises determining gradient waveform parameters subject to hardware constraints specified using a differential equation, the differential equation specified in part using the second information.

18. A low-field magnetic resonance imaging (MRI) system, comprising:
a magnetics system comprising a plurality of magnetics components configured to produce magnetic fields for performing magnetic resonance imaging, the plurality of magnetics components comprising a gradient coil and a gradient power amplifier for driving the gradient coil; and
at least one controller configured to operate one or more of the plurality of magnetics components, wherein the at least one controller is configured to:
access first information indicative of a gradient waveform;
access second information indicative of hardware constraints of the low-field MRI system;
determine the gradient waveform using the first information and the second information, wherein the gradient waveform is a trapezoidal gradient waveform having a non-linear ramp-up portion and/or a non-linear ramp-down portion; and
generate the gradient waveform.

19. The low-field MRI system of claim 18 , wherein the magnetics system comprises at least one permanent magnet configured to generate a B 0 magnetic field having a strength less than 0.2 T.

20. The low-field MRI system of claim 18 , wherein the magnetics system further comprises at least one permanent magnet configured to generate a B 0 magnetic field having a strength in a range from 50 mT to 0.1 T.

Assignees

• Hyperfine Operations Inc

Inventors

• Dyvorne Hadrien A
• Sacolick Laura
• O'Halloran Rafael
• Lazarus Carole
• Twieg Michael

Classifications

• G01R33/383

  using permanent magnets · CPC title

• G01R33/385 Primary

  using gradient magnetic field coils · CPC title

• G01R33/3802

  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

• G01R33/543

  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

• G01R33/56572

  caused by a distortion of a gradient magnetic field, e.g. non-linearity of a gradient magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title