Magnetic particle imaging devices and methods

Patent metadata

Field	Value
Publication number	US-10667716-B2
Application number	US-201715674234-A
Country	US
Kind code	B2
Filing date	Aug 10, 2017
Priority date	Jun 23, 2008
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A magnetic particle imaging device is provided. The device includes a magnetic field source configured to produce a magnetic field having a non-saturating magnetic field region, an excitation signal source configured to produce an excitation signal in the non-saturating magnetic field region that produces a detectable signal from magnetic particles in the non-saturating magnetic field region, and a signal processor configured to convert a detected signal into an image of the magnetic particles. Aspects of the present disclosure also include methods of imaging magnetic particles in a sample, and methods of producing an image of magnetic particles in a subject. The subject devices and methods find use in a variety of applications, such as medical imaging applications.

First claim

What is claimed is:

1. A magnetic particle imaging device, comprising:
a gradient magnetic field source arranged proximate an imaging region of the magnetic particle imaging device, the gradient magnetic field source configured to produce a gradient magnetic field within the imaging region of the magnetic particle imaging device such that the gradient magnetic field defines a field-free line (FFL);
a scanning magnetic field source arranged proximate the imaging region of the magnetic particle imaging device, the scanning magnetic field source being configured to produce a scanning magnetic field to position the FFL in the imaging region;
an excitation signal source arranged proximate the imaging region of the magnetic particle imaging device, the excitation signal source being configured to produce an excitation magnetic field that induces a signal from a magnetic tracer in an object under observation;
a receiver arranged proximate the imaging region, the receiver being configured to receive the signal from the magnetic tracer in the object under observation; and
a signal processor configured to be in communication with the receiver, the signal processor being configured to convert the signal into an image of the magnetic tracer,
wherein the gradient magnetic field source is configured to mechanically rotate relative to the object under observation,
wherein the scanning magnetic field source is configured to move the FFL in a direction perpendicular to the FFL, and
wherein at least one of the gradient magnetic field source and the scanning magnetic field source are configured to mechanically rotate relative to the object under observation in a plane formed by the FFL and the direction perpendicular to the FFL.

2. The device of claim 1 , wherein the gradient magnetic field source comprises a combination of electromagnets, permanent magnets, and soft magnetic materials.

3. The device of claim 1 , wherein the gradient magnetic field source comprises a combination of electromagnets and soft magnetic materials.

4. The device of claim 1 , wherein the gradient magnetic field source comprises permanent magnets.

5. The device of claim 4 , wherein the permanent magnets are configured in a halbach array.

6. The device of claim 4 , wherein the permanent magnets are configured in a pair of halbach arrays.

7. The device of claim 1 , wherein the scanning magnetic field source comprises electromagnets.

8. The device of claim 1 , wherein the scanning magnetic field source comprises a combination of electromagnets, permanent magnets, and soft magnetic materials.

9. The device of claim 1 , wherein the scanning magnetic field source comprises a combination of electromagnets and soft magnetic materials.

10. The device of claim 1 , wherein the gradient magnetic field source and the scanning magnetic field source are the same.

11. The device of claim 1 , wherein the magnetic particle imaging device is configured to position the FFL by a combination of dynamic scanning using the scanning magnetic field source and physical translation of the object under observation relative to the device or physical translation of the device relative to the object under observation.

12. The device of claim 1 , wherein the excitation magnetic field comprises fields produced by at least two excitation field sources.

13. The device of claim 11 , wherein scanning magnetic field source is configured to implement a raster pulse sequence for raster scanning of the imaging region.

14. The device of claim 13 , wherein the raster scanning prescribes an overlapping FFL trajectory.

15. The device of claim 1 , wherein the signal processor is further configured to output a projection image.

16. The device of claim 1 , wherein a collection of projected image slices is acquired, each projected image slice of the collection having a unique rotation angle associated therewith.

17. The device of claim 16 , wherein the signal processor is further configured to produce a tomographic image from the collection of projected image slices using computed tomography techniques.

18. A method of producing an image of a magnetic tracer in a sample, comprising:
applying a gradient magnetic field to the sample containing the magnetic tracer, the gradient magnetic field defining a field-free line (FFL);
applying a scanning magnetic field in superposition with the gradient magnetic field defining the FFL to move the FFL in the imaging region in a direction perpendicular to the FFL;
mechanically rotating a source of the applied gradient magnetic field relative to the sample to position the FFL;
mechanically rotating at least one of the source of the applied gradient magnetic field and a source of the scanning magnetic field relative to the sample in a plane formed by the FFL and the direction perpendicular to the FFL;
applying an excitation magnetic field to the sample to produce a detectable signal from the magnetic tracer;
receiving a signal from the magnetic tracer; and
analyzing the received signal to produce an image of the magnetic tracer in the sample.

19. The method of claim 18 , wherein the analyzing comprises correlating the received signal with a position of the FFL when the signal was received.

20. The method of claim 18 , further comprising positioning the FFL by a combination of dynamic scanning using the scanning magnetic field and physical translation of the sample relative to a source of the gradient magnetic field or physical translation of the source of the gradient magnetic field relative to the sample.

21. The method of claim 18 , wherein the applying the excitation magnetic field comprises applying a radio-frequency excitation magnetic field in superposition with the gradient magnetic field defining the FFL.

22. The method of claim 18 , further comprising shielding with a radio-frequency shield a receiver that receives the signal.

23. A method of producing an image of a magnetic tracer in a sample, comprising:
applying a gradient magnetic field to the sample containing the magnetic tracer, the gradient magnetic field defining a field-free line (FFL);
applying an excitation magnetic field to the sample to produce a detectable signal from the magnetic tracer;
applying a scanning magnetic field in superposition with the gradient magnetic field defining the FFL to position the FFL;
receiving a signal from the magnetic tracer; and
analyzing the received signal to produce an image of the magnetic tracer in the sample,
wherein a frequency of the scanning magnetic field is lower than a frequency of the excitation magnetic field, and
wherein the scanning magnetic field is a homogeneous magnetic field.

24. A magnetic particle imaging device, comprising:
a gradient magnetic field source arranged proximate an imaging region of the magnetic particle imaging device, the gradient magnetic field source configured to produce a gradient magnetic field within the imaging region of the magnetic particle imaging device such that the gradient magnetic field defines a field-free line (FFL);
a scanning magnetic field source arranged proximate the imaging region of the magnetic particle imaging device, the scanning magnetic field source being configured to produce a scanning magnetic field to position the FFL in the imaging region;
an excitation signal source arranged proximate the imaging region of the magnetic particle imaging device, the excitation signal source being configured to produ

Assignees

• Univ California

Inventors

• Goodwill Patrick W
• Conolly Steven M

Classifications

• G01R33/10

  Plotting field distribution {; Measuring field distribution} · CPC title

• A61B5/7239

  using differentiation including higher order derivatives · CPC title

• A61B5/0515 Primary

  Magnetic particle imaging · CPC title

• A61B2576/00

  Medical imaging apparatus involving image processing or analysis (A61B1/00009, A61B6/52 and A61B8/52 take precedence) · CPC title

• G01R33/1276

  of magnetic particles, e.g. imaging of magnetic nanoparticles (G01R33/1269 takes precedence) · CPC title