Method and device for establishing excitation parameters for MR imaging

Patent metadata

Field	Value
Publication number	US-9103896-B2
Application number	US-201213406554-A
Country	US
Kind code	B2
Filing date	Feb 28, 2012
Priority date	Mar 1, 2011
Publication date	Aug 11, 2015
Grant date	Aug 11, 2015

Abstract

A method and a device for establishing excitation parameters, in particular for establishing an excitation profile, for MR imaging, are proposed. Elements of a k-space covariance matrix are determined for signal noise in k-space data which is captured using a plurality of receive channels in the context of data captured at an examination object. Elements of at least one image space covariance matrix are mathematically determined for a plurality of voxels of the examination object as a function of the k-space covariance matrix. The excitation parameters are established as a function of the determined elements of the at least one image space covariance matrix.

First claim

The invention claimed is:

1. A method for establishing excitation parameters for a MR imaging captured by an MR device, comprising:
parallel exciting the MR device using a plurality of transmit channels of the MR device;
parallel capturing image data of an examination object using a plurality of receive channels of the MR device;
determining elements of a k-space covariance matrix for a signal noise of the captured image data in a k-space;
mathematically determining elements of an image space covariance matrix for a plurality of voxels in a region of interest of the examination object as a function of the k-space covariance matrix; and
establishing the excitation parameters as a function of the elements of the image space covariance matrix,
wherein an excitation profile is determined by minimizing an evaluation function that is dependent on diagonal elements of the image space covariance matrix corresponding to the plurality of voxels in the region of interest.

2. The method as claimed in claim 1 , wherein the excitation parameters comprise information known prior to capturing the image data and are determined based on the elements of the image space covariance matrix that satisfy a predefined condition.

3. The method as claimed in claim 2 , wherein a covariance of the prior information is determined based on geometry factors for the plurality of voxels in the region of interest that are reduced in comparison with a homogeneous excitation.

4. The method as claimed in claim 2 , wherein a covariance matrix of the prior information is determined based on the elements of the image space covariance matrix that are reduced in comparison with a homogeneous excitation.

5. The method as claimed in claim 2 , wherein a covariance matrix of the prior information is determined by an equation

C
0

-
1

=

(

E
†

⁢

C

-
1

⁢
E

)

-

1
2

⁢

D
ρ

-
1

⁡

(

E
†

⁢

C

-
1

⁢
E

)

-

1
2

-
I

,

where C 0 designates the covariance matrix of the prior information, E designates an encoding matrix, C designates the k-space covariance matrix, D ρ designates the image space covariance matrix, and I designates a unit matrix.

6. The method as claimed in claim 2 , wherein a covariance of the prior information is determined iteratively.

7. The method as claimed in claim 2 , wherein a covariance of the prior information is mathematically determined automatically subject to constraints.

8. The method as claimed in claim 1 ,
wherein the elements of the image space covariance matrix are determined mathematically for a plurality of sets of excitation parameters and are assigned to a corresponding set of excitation parameters, and
wherein the excitation parameters are established as a function of the elements of the image space covariance matrix each determined for the plurality of sets of excitation parameters.

9. The method as claimed in claim 8 , wherein the plurality of sets of excitation parameters correspond to a plurality of excitation profiles.

10. The method as claimed in claim 1 , wherein the evaluation function is represented by
Tr ( RC ρ R † )
wherein Tr designates a trace operator, C ρ designates the image space covariance matrix, and R designates a projection operator for the region of interest, and
wherein the minimization is subject to a constraint that signals from the region of interest are not reduced.

11. The method as claimed in claim 1 , wherein the elements of the k-space covariance matrix are determined by a covariance of data in the k-space captured using different recording coils.

12. The method as claimed in claim 1 , wherein the excitation parameters are determined for measuring variables that are dependent on an echo time.

13. The method as claimed in claim 1 , wherein the excitation parameters are determined for a multi-echo imaging sequence.

14. The method as claimed in claim 1 , wherein the excitation parameters are determined such that different portions of the captured image data are suppressed for different echo times.

15. A method for establishing excitation parameters for a MR imaging captured by an MR device, comprising:
parallel exciting the MR device using a plurality of transmit channels of the MR device;
parallel capturing image data of an examination object using a plurality of receive channels of the MR device;
determining elements of a k-space covariance matrix for a signal noise of the captured image data in a k-space;
mathematically determining elements of an image space covariance matrix for a plurality of voxels in a region of interest of the examination object as a function of the k-space covariance matrix; and
establishing the excitation parameters as a function of the elements of the image space covariance matrix,
wherein the elements of the image space covariance matrix are determined mathematically for a plurality of sets of excitation parameters and are assigned to a corresponding set of excitation parameters,
wherein the excitation parameters are established as a function of the elements of the image space covariance matrix each determined for the plurality of sets of excitation parameters,
wherein the plurality of sets of excitation parameters correspond to a plurality of excitation profiles, and
wherein the plurality of excitation profiles are sinusoidally or

Assignees

• Gross Patrick
• Siemens Ag

Inventors

• Gross Patrick

Classifications

• G01R33/5612 Primary

  Parallel RF transmission, i.e. RF pulse transmission using a plurality of independent transmission channels · CPC title