Hysteresis effect-based field free point-magnetic particle imaging method

Patent metadata

Field	Value
Publication number	US-11779237-B2
Application number	US-202217828026-A
Country	US
Kind code	B2
Filing date	May 30, 2022
Priority date	Jul 21, 2021
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

A hysteresis effect-based Field Free Point-Magnetic Particle Imaging (FFP-MPI) method includes the following steps: acquiring a hysteresis loop model of Superparamagnetic Iron Oxide Nanoparticles (SPIOs); calculating to obtain a Point Spread Function (PSF) of the SPIOs on the basis of a sinusoidal excitation magnetic field and the hysteresis loop model of the SPIOs; acquiring an original reconstructed image of FFP-MPI on the basis an FFP moving track and a voltage signal; performing deconvolution on the original image with respect to the PSF considering an hysteresis effect, so as to obtain a final reconstructed image; the artifacts and phase errors of image reconstruction caused by the hysteresis effect of the SPIOs with large particle sizes are reduced, the deficiency in reconstruction by the traditional reconstruction method that ignores the hysteresis effect is overcome, the reconstruction speed and the resolution are greatly improved, and the application range of the SPIOs is expanded.

First claim

The invention claimed is:

1. A hysteresis effect-based Field Free Point-Magnetic Particle Imaging (FFP-MPI) method using a Magnetic Particle Imaging (MPI) device, comprising the following steps:
S1: acquiring a hysteresis loop model of Superparamagnetic Iron Oxide Nanoparticles (SPIOs) by measuring parameters through a Magnetic Particle Spectrometer (MPS) and combining an M-H hysteresis curve model of a hysteresis effect,
wherein the SPIOs are excited by a sinusoidal excitation magnetic field in the MPI device at a frequency of 20-45 kHz, and
wherein the M-H hysteresis curve model is:

{

dM
dH

=

1

(

1
+
c

)

⁢

(

M
1

-
M

)

δ
⁢
k
/

μ
0

-

α
⁡
(

M
1

-
M

)

+

c

(

1
+
c

)

⁢

dM
1

dH

M
1

=

M
s

(

coth
⁡
(

H
+

α
⁢
M

a

)

-

a

H
+

α
⁢
M

)

;

S2: calculating to obtain a Point Spread Function (PSF) of the SPIOs,
wherein the step for calculating to obtain the PSF of the SPIOs further comprising:
(a) exciting the SPIOs by the sinusoidal excitation magnetic field in the MPI device, an externally applied excitation magnetic field (H) is calculated by the MPI device using formula (1.2):
H ( t )= A cos(ω t ),

(b) substituting the formula (1.2) into the hysteresis loop model of the SPIOs to obtain a function of a magnetization vector of the SPIOs along with the time, and
(c) obtaining the Point Spread Function (PSF) by solving a derivative of the function of the magnetization vector of the SPIOs with respect to time by using formula (1.3):

PSF
=

dM
⁡
(
t
)

dt

=

A
⁢

ωsin
⁡
(

ω
⁢
t

)

⁢

(

1

(

1
+
c

)

⁢

(

M
1

-
M

)

Assignees

• Beijing Univ Of Aeronautics And Astronautics
• Univ Beihang

Inventors

• Tian Jie
• Li Yimeng
• An Yu
• Zhong Jing
• He Jie
• Zhang Bo

Classifications

• A61B5/0515 Primary

  Magnetic particle imaging · CPC title

• G01R33/1276 Primary

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

• G01R33/14

  Measuring or plotting hysteresis curves {(G01R33/1207 takes precedence)} · CPC title

• G01R33/24

  for measuring direction or magnitude of magnetic fields or magnetic flux · CPC title

• Y02A90/30

  Assessment of water resources · CPC title