System for and method of rapid peripheral nerve stimulation assessment of gradient coils

Patent metadata

Field	Value
Publication number	US-12268508-B2
Application number	US-202017118155-A
Country	US
Kind code	B2
Filing date	Dec 10, 2020
Priority date	Dec 10, 2019
Publication date	Apr 8, 2025
Grant date	Apr 8, 2025

Abstract

A method for assessing peripheral nerve stimulation (PNS) for a coil geometry includes retrieving a PNS Huygens' P-matrix for a body model. The PNS Huygens' P-matrix is defined on a Huygens' surface enclosing the body model. The method further includes generating a coil specific PNS P-matrix for the coil geometry based on at least the PNS Huygens' P-matrix for the body model, determining at least one PNS threshold for the coil geometry based on the coil specific PNS P-matrix, and storing the at least one PNS threshold in a storage device.

First claim

The invention claimed is:

1. A method for assessing peripheral nerve stimulation (PNS) for a coil geometry, the method comprising:
retrieving a PNS Huygens' penalty matrix (P-matrix) for a body model, the PNS Huygens' P-matrix defined on a Huygens' surface enclosing the body model;
generating a coil specific PNS P-matrix for the coil geometry based on at least the PNS Huygens' P-matrix for the body model;
determining at least one PNS threshold for the coil geometry based on the coil specific PNS P-matrix;
storing the at least one PNS threshold in a storage device;
determining an adjustment of one or more of a parameter of or position of the coil geometry based on the at least one PNS threshold for the coil geometry; and
adjusting the one or more of a parameter or a position of the coil geometry based on the determined adjustment.

2. The method according to claim 1 , wherein the coil geometry is a gradient coil geometry.

3. The method according to claim 1 , wherein the coil geometry is a magneto-stimulation device coil geometry.

4. The method according to claim 1 , wherein the coil geometry is a coil former shape.

5. The method according to claim 1 , wherein the coil geometry is a coil winding pattern.

6. The method according to claim 4 , wherein generating the coil specific PNS P-matrix for a coil former shape is further based on a mapping matrix.

7. The method according to claim 6 , wherein generating the coil specific PNS P-matrix for a coil former shape is given by:
P D =P H M

where P D is the coil specific PNS P-matrix for the coil former shape, P H is the PNS Huygens' P-matrix and M is the mapping matrix.

8. The method according to claim 6 , further comprising generating the mapping matrix by solving a set of linear matrix equations.

9. The method according to claim 5 , wherein generating the coil specific PNS P-matrix for a coil winding pattern is further based on a mapping vector.

10. The method according to claim 9 , wherein generating the coil specific PNS P-matrix for a coil winding pattern is given by:
P D =P H m

where P D is the coil specific PNS P-matrix for the coil winding pattern, P H is the PNS Huygens' P-matrix and m is the mapping vector.

11. The method according to claim 10 , wherein determining at least one PNS threshold for the gradient coil geometry based on the coil specific PNS P-matrix for the coil winding pattern includes determining an inverse of the maximum absolute coil specific PNS P-matrix as given by:
max{| P H m| −1 }

12. The method according to claim 1 , wherein the Huygens' surface is configured to enclose the body model and maintain a predetermined minimum distance between the Huygens' surface and a boundary of the body model.

13. The method according to claim 1 , wherein the coil specific PNS P-matrix for the gradient coil geometry is a linear P-matrix.

14. A magnetic resonance imaging (MRI) system comprising:
a magnet system configured to generate a polarizing magnetic field about at least a portion of a subject;
a magnetic gradient system including a plurality of gradient coils configured to apply at least one gradient field to the polarizing magnetic field;
a radio frequency (RF) system configured to apply an excitation field to the subject and to receive MR data from the subject using a coil array; and
a computer system programmed to:
retrieve a peripheral nerve stimulation (PNS) Huygens' penalty matrix (P-matrix) for a body model, the PNS Huygens' P-matrix defined on a Huygens' surface enclosing the body model;
generate a coil specific PNS P-matrix for a predetermined gradient coil geometry based on at least the PNS Huygens' P-matrix for the body model;
determine at least one PNS threshold for the gradient coil geometry based on the coil specific PNS P-matrix;
store the at least one PNS threshold in a storage device;
determine an adjustment of one or more parameters of the gradient coil geometry based on the at least one PNS threshold for the gradient coil geometry; and
adjust the one or more parameters of the gradient coil geometry based on the determined adjustment.

15. The MRI system according to claim 14 , wherein the gradient coil geometry is a coil former shape.

16. The MRI system according to claim 14 , wherein the gradient coil geometry is a coil winding pattern.

17. A method for optimizing a design of a gradient coil geometry, the method comprising:
creating a current density distribution of the gradient coil geometry;
determining a B-field generated by each stream function basis associated with the current density distribution;
determining a coil specific peripheral nerve stimulation penalty matrix (PNS P-matrix) for the gradient coil geometry based on at least a PNS Huygens' P-matrix for a body model, the PNS Huygens' P-matrix defined on a Huygens' surface enclosing the body model;
determining a current density pattern using an optimization process including the coil specific PNS P-matrix for the gradient coil geometry;
storing the current density pattern; and
configuring the gradient coil geometry based on the current density pattern.

18. The method according to claim 17 , wherein the gradient coil geometry is a coil former shape.

19. The method according to claim 18 , wherein determining the coil specific PNS P-matrix for the coil former shape is given by:
P D =P H M

where P D is the coil specific PNS P-matrix for the coil former shape, P H is the PNS Huygens' P-matrix and M is a mapping matrix.

20. The method according to claim 17 , wherein the Huygens' surface is configured to enclose the body model and maintain a predetermined minimum distance between the Huygens' surface and a boundary of the body model.

Assignees

• Massachusetts Gen Hospital

Inventors

• Davids Mathias
• Wald Lawrence L
• Guerin Bastien

Classifications

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• A61B5/0515

  Magnetic particle imaging · CPC title

• G01R33/0029

  Treating the measured signals, e.g. removing offset or noise · CPC title

• A61B2560/04

  Constructional details of apparatus · CPC title

• A61B5/311 Primary

  for nerve conduction study [NCS] · CPC title