Systems and methods for imaging and quantifying tissue magnetism with magnetic resonance imaging

Patent metadata

Field	Value
Publication number	US-9285449-B2
Application number	US-201213517633-A
Country	US
Kind code	B2
Filing date	Jun 14, 2012
Priority date	Jun 15, 2011
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Systems and methods for imaging and quantifying tissue magnetism with magnetic resonance imaging (MRI) are disclosed. According to an aspect, a method for MRI includes using an MRI system to acquire multiple image echoes of an object. The method also includes combining the image echoes. Further, the method includes generating an image of the object based on the combined image echoes for depicting a characteristic of the object.

First claim

What is claimed:

1. A method for magnetic resonance imaging (MRI), the method comprising:
using an MRI system to acquire a plurality of image echoes of an object at a plurality of echo times;
combining the plurality of image echoes using a weighted averaging technique;
generating an image of the object based on the combined image echoes for depicting a characteristic of the object; and
applying a varying-radius spherical mean value (SMV) filtering technique to separate tissue phase from background phase; and wherein the radius of the sphere decreases towards the edges of the object, and
wherein the filtering technique is conducted in a frequency domain.

2. The method of claim 1 , wherein using the MRI system comprises using the MRI system to acquire the plurality of image echoes at a plurality of echo times and at a single orientation or a plurality of orientations of the object relative to a magnetic field generated by the MRI system.

3. The method of claim 1 , wherein using the MRI system comprises using the MRI system to acquire the image echoes by one of spin wrap trajectory, interleaved spiral trajectory, and three-dimensional (3D) echo planar imaging (EPI) trajectory; and 3D echo planar imaging being corrected by use of a navigator phase.

4. The method of claim 1 , wherein combining the image echoes comprises applying one of multi-echo averaging and multi-echo weighted averaging to the image echoes.

5. The method of claim 1 , wherein generating the image of the object comprises generating an image of magnetic susceptibility based on the combined image echoes, and
wherein the image echoes are acquired at a plurality of echo times.

6. The method of claim 5 , wherein generating the image of magnetic susceptibility comprises:
generating a phase image based on the combined image echoes; and
applying a Laplacian operator to the phase image to separate magnetic field originating from magnetic sources outside a field of view.

7. The method of claim 1 , wherein generating the image comprises:
partitioning the frequency domain of the phase image into a trusted region and an ill-posed region; and
one of:
applying a derivative and Fourier relationship to the combined image echoes; and
applying a compressed sensing technique to estimate the underlying magnetic susceptibility values in the trusted region and the ill-posed region.

8. A magnetic resonance imaging (MRI) system comprising:
an MRI device configured to acquire a plurality of image echoes of an object at a plurality of echo times; and
an image generator configured to:
combine the plurality of image echoes using a weighted averaging technique;
generate an image of the object based on the combined image echoes for depicting a characteristic of the object; and
apply a varying-radius spherical mean value (SMV) filtering technique to separate tissue phase from background phase; and wherein the radius of the sphere decreases towards the edges of the object, and
wherein the filtering technique is conducted in a frequency domain.

9. The MRI system of claim 8 , wherein the MRI device is configured to acquire the plurality of image echoes at a plurality of echo times and at a single orientation or a plurality of orientations of the object relative to a magnetic field generated by the MRI system.

10. The MRI system of claim 8 , wherein the MRI device is configured to acquire the plurality of image echoes by one of spin wrap trajectory, interleaved spiral trajectory, and three-dimensional (3D) echo planar imaging (EPI) trajectory; and 3D echo planar imaging being corrected by use of a navigator phase.

11. The MRI system of claim 8 , wherein the image generator is configured to apply one of multi-echo averaging and multi-echo weighted averaging to the image echoes, and
wherein the image echoes are acquired at a plurality of echo times.

12. The MRI system of claim 8 , wherein the image generator is configured to generate an image of magnetic susceptibility based on the combined image echoes.

13. The MRI system of claim 12 , wherein the image generator is configured to:
generate a phase image based on the combined image echoes; and
apply a Laplacian operator to the phase image to separate magnetic field originating from magnetic sources outside a field of view.

14. The MRI system of claim 8 , wherein the image generator is configured to:
partition the frequency domain of the phase image into a trusted region and an ill-posed region; and
one of:
apply a derivative and Fourier relationship to the combined image echoes; and
apply a compressed sensing technique to estimate the underlying magnetic susceptibility values in the trusted region and the ill-posed region.

Assignees

• Liu Chunlei
• Li Wei
• Wu Bing

Inventors

• Liu Chunlei
• Li Wei
• Wu Bing

Classifications

• G01R33/443

  Assessment of an electric or a magnetic field, e.g. spatial mapping, determination of a B0 drift or dosimetry · CPC title

• G01R33/4824

  using a non-Cartesian trajectory · CPC title

• G01R33/56509

  due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence) · CPC title

• G01R33/5616 Primary

  using gradient refocusing, e.g. EPI · CPC title

• G01R33/4822

  in three dimensions · CPC title