MRI streak-artifact suppression, system and method

Patent metadata

Field	Value
Publication number	US-12085632-B2
Application number	US-201917253023-A
Country	US
Kind code	B2
Filing date	Jun 19, 2019
Priority date	Jun 19, 2018
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A method for producing a streak-suppressed magnetic resonance (MR) image of a subject includes generating an interference covariance matrix {circumflex over ( )}R front N coil images Ij (x,y), j={1, 2, . . . , N}, each of the N coil images Ij (x,y) corresponding to MR signals detected by a respective one of a phased array of N coils of an MRI scanner. The MR signals originate in voxels of the subject corresponding to an artifact-corrupted region of a coil image. Coordinates (x,y) correspond to a location within a cross-sectional plane of the subject. The method also includes, for subject-regions of cross-sectional plane centered at a respective location (x,y), determining a coil weight vector W (x,y) from {circumflex over ( )}R. The method also includes generating the streak-suppressed MR image as a weighted sum of the coil images Ij (x,y), each weight of the weighted sum being Wj* (x,y), a j th element of a complex conjugate of coil weight vector W (x,y).

First claim

What is claimed is:

1. A method for producing a streak-suppressed magnetic resonance (MR) image of a subject comprising:
generating an interference covariance matrix {circumflex over (R)} from N coil images I j (x, y), j={1, 2, . . . , N}, each of the N coil images I j (x, y) corresponding to MR signals detected by a respective one of a phased array of N coils of an MRI scanner, at least some of the MR signals originating in a first plurality of voxels of the subject corresponding to an artifact-region of a coil image corrupted by an artifact, coordinates (x, y) corresponding to locations within a cross-sectional plane of the subject;
for each of a plurality of subject-regions of the cross-sectional plane centered at a respective location (x, y), determining a coil weight vector W (x, y) from the interference covariance matrix {circumflex over (R)}; and
generating the streak-suppressed MR image by combining a plurality of coil images using a weighted sum of the N coil images I j (x, y), each weight of the weighted sum being W* j (x, y), a j th element of a complex conjugate of the coil weight vector W (x, y).

2. The method of claim 1 , the first plurality of voxels being Q R in number, and, in the step of generating the interference covariance matrix:
the interference covariance matrix R being an N×N matrix, each matrix element {circumflex over (R)}(j, k) being proportional to

1

(

Q
R

-
1

)

·

∑

(

x
c

,

y
c

)

⁢

I
j

⁡

(

x
c

,

y
c

)

⁢

I
k
*

⁡

(

x
c

,

y
c

)

,

 where summation Σ is over respective ranges of coordinates x c and y c corresponding to the first plurality of voxels, where I* k denotes the complex conjugate of a coil image corresponding to the k th one of the N coils.

3. The method of claim 1 , the second plurality of voxels being Q s in number, and, in the step of generating the signal correlation matrix Ŝ(x,y):
the signal correlation matrix Ŝ being an N×N matrix, a matrix element Ŝ (x,y) (j, k) being proportional to

1

(

Q
S

-
1

)

·

∑

(

x
c

,

y
c

)

⁢

I
j

⁡

(

x
c

,

y
c

)

⁢

I
k
*

⁡

(

x
c

,

y
c

)

,

 where summation Σ is over respective ranges of coordinates x c and y c corresponding to the second plurality of voxels centered at voxel coordinate (x, y), where I* k denotes the complex conjugate of a coil image corresponding to the k th one of the N coils.

4. The method of claim 1 , I(x, y) denoting the streak-suppressed MR image, and in the step of generating the streak-suppressed MR image, I(x, y)=Σ j=1 N W* j (x, y)I j (x, y).

5. The method of claim 1 , further comprising, before determining the coil weight vector W (x, y) for at least one of the plurality of subject-regions: decreasing a condition number of the interference covariance matrix {circumflex over (R)}.

6. The method of claim 5 , the interference covariance matrix {circumflex over (R)} being an N×N matrix, decreasing the condition number comprising regularizing the interference covariance matrix {circumflex over (R)} by adding thereto an N×N identity matrix multiplied by a scalar.

7. The method of claim 1 , further comprising:
generating a signal correlation matrix Ŝ (x,y) of the subject-region from the N coil images I j (x, y) corresponding to MR signals originating in a second plurality of voxels corresponding to the subject-region, and
determining a coil weight vector W (x, y) equal to an eigenvector of a ma

Assignees

• Univ Arizona

Inventors

• Mandava Sagar
• Altbach Maria I
• Bilgin Ali
• Martin Diego R
• Keerthivasan Mahesh Bharath

Classifications

• G01R33/3664

  Switching for purposes other than coil coupling or decoupling, e.g. switching between a phased array mode and a quadrature mode, switching between surface coil modes of different geometrical shapes, switching from a whole body reception coil to a local reception coil or switching for automatic coil selection in moving table MR or for changing the field-of-view (G01R33/3671 takes precedence) · CPC title

• G01R33/3415

  comprising arrays of sub-coils {, i.e. phased-array coils with flexible receiver channels} · CPC title

• G01R33/56572 Primary

  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

• G01R33/4824 Primary

  using a non-Cartesian trajectory · CPC title