Controlling magnetic resonance systems

Patent metadata

Field	Value
Publication number	US-9594137-B2
Application number	US-201313847859-A
Country	US
Kind code	B2
Filing date	Mar 20, 2013
Priority date	Mar 30, 2012
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Methods for controlling magnetic resonance systems having a plurality of high frequency transmission channels through which HF pulse trains are emitted in parallel during operation are described. The methods involves specifying a joint reference pulse train for a plurality of the high frequency transmission channels, and determining a transmission scaling factor for each of the high frequency transmission channels in an HF pulse-optimization method by taking into consideration a specified target magnetization to calculate the HF pulse trains for the transmission channels on the basis of the reference pulse train. During calculation of the transmission scaling factors, a target function is created independently of a target magnetization difference in at least a first optimization mode of the HF pulse-optimization method. The target magnetization difference is considered in the HF pulse-optimization method by way of a boundary condition function instead. Pulse optimization devices and magnetic resonance systems are described.

First claim

The invention claimed is:

1. A method for controlling a magnetic resonance system, the magnetic resonance system comprising a plurality of high frequency transmission channels, the method comprising:
specifying a joint reference pulse train for a plurality of the high frequency transmission channels;
determining, in a high-frequency (HF) pulse-optimization, a transmission scaling factor for each high frequency transmission channel of the plurality of high frequency transmission channels, wherein each transmission scaling factor takes into consideration a specified target magnetization;
calculating an individual HF pulse train for each high frequency transmission channel of the plurality of high frequency transmission channels based on the reference pulse train and the transmission scaling factor for the respective high frequency transmission channel; and
emitting a multi-channel pulse train via a high frequency transceiver, the multi-channel pulse train comprising the calculated HF pulse trains,
wherein, in determining the transmission scaling factors in the HF pulse optimization:
(1) a target function is created independently of a target magnetization difference during calculation of the transmission scaling factors, the target magnetization difference being a measure of a difference in an actual magnetization theoretically attained with high frequency pulses determined during the HF pulse-optimization from the specified target magnetization, and wherein the target magnetization difference is considered in the HF pulse-optimization by way of a boundary condition function; or
(2) the target function comprises the target magnetization difference and no HF exposure value of an object to be examined, and wherein the HF exposure value is considered by way of the boundary condition function.

2. The method of claim 1 , wherein the target function is created independently of the target magnetization difference and the target magnetization difference is considered in the HF pulse-optimization by way of the boundary condition function, and wherein the target function comprises at least one HF exposure value of an object to be examined.

3. The method of claim 1 , wherein the target function comprises the target magnetization difference and no HF exposure value of the object to be examined, and wherein the HF exposure value is considered by way of the boundary condition function.

4. The method of claim 3 , further comprising providing an optimization mode indicator.

5. The method of claim 2 , wherein the HF exposure value comprises a HF local exposure value.

6. The method of claim 3 , wherein the HF exposure value comprises a HF local exposure value.

7. The method of claim 1 , wherein the boundary condition function defines a permissible difference in a parameter value from a reference parameter value.

8. The method of claim 2 , wherein the boundary condition function defines a permissible difference in a parameter value from a reference parameter value.

9. The method of claim 3 , wherein the boundary condition function defines a permissible difference in a parameter value from a reference parameter value.

10. The method of claim 4 , wherein the boundary condition function defines a permissible difference in a parameter value from a reference parameter value.

11. The method of claim 7 , wherein the reference parameter value is defined based on a parameter value of the relevant parameter achievable in a basic excitation mode.

12. The method of claim 8 , wherein the reference parameter value is defined based on a parameter value of the relevant parameter achievable in a basic excitation mode.

13. The method of claim 9 , wherein the reference parameter value is defined based on a parameter value of the relevant parameter achievable in a basic excitation mode.

14. The method of claim 10 , wherein the reference parameter value is defined based on a parameter value of the relevant parameter achievable in a basic excitation mode.

15. The method of claim 11 , wherein a relational value is acquired and, based thereon, the reference parameter value is defined relative to the parameter value of the relevant parameter achievable in the basic excitation mode.

16. The method of claim 12 , wherein a relational value is acquired and, based thereon, the reference parameter value is defined relative to the parameter value of the relevant parameter achievable in the basic excitation mode.

17. The method of claim 13 , wherein a relational value is acquired and, based thereon, the reference parameter value is defined relative to the parameter value of the relevant parameter achievable in the basic excitation mode.

18. The method of claim 14 , wherein a relational value is acquired and, based thereon, the reference parameter value is defined relative to the parameter value of the relevant parameter achievable in the basic excitation mode.

19. The method of claim 1 , wherein two transmission channels of the magnetic resonance system are controlled.

20. A pulse optimization device for a magnetic resonance system with a plurality of high frequency transmission channels, the pulse optimization device comprising:
a controller configured to determine, in a high-frequency (HF) pulse-optimization, a transmission scaling factor for each high frequency transmission channel of the plurality of high frequency transmission channels for a reference pulse train jointly specified for the high frequency transmission channels, wherein each transmission scaling factor takes into consideration a specified target magnetization;
wherein, in determining the transmission scaling factors in the HF pulse optimization, the controller is further configured to create a target function, wherein:
(1) the target function is created independently of a target magnetization difference during calculation of the transmission scaling factors, the target magnetization difference being a measure of a difference in an actual magnetization theoretically attained with high frequency pulses determined during the HF pulse-optimization from the specified target magnetization, and wherein the target magnetization difference is considered in the HF pulse-optimization by way of a boundary condition function; or
(2) the target function comprises the target magnetization difference and no HF exposure value of an object to be examined, and wherein the HF exposure value is considered by way of the boundary condition function.

21. A magnetic resonance system comprising:
a plurality of high frequency transmission channels;
a controller configured to emit HF pulse trains in parallel in order to carry out a desired measurement via the high frequency transmission channels; and
a pulse optimization device configured to determine, in a high-frequency (HF) pulse-optimization, a transmission scaling factor for each high frequency transmission channel of the plurality of high frequency transmission channels for a reference pulse train jointly specified for the high frequency transmission channels, wherein each transmission scaling factor takes into consideration a specified target magnetization;
wherein, in determining the transmission scaling factors in the HF pulse optimization, the pulse optimization device is further configured to create a target function, wherein:
(1) the target function is created independently of a target magnetization difference during calculation of the transmission scaling factors, the target magnetization difference being a measure of a difference in an actua

Assignees

• Ritter Dieter
• Siemens Ag

Inventors

• Ritter Dieter

Classifications

• G01R33/543 Primary

  Control of the operation of the MR system, e.g. setting of acquisition parameters prior to or during MR data acquisition, dynamic shimming, use of one or more scout images for scan plane prescription (G01R33/546 takes precedence) · CPC title

• G01R33/5659 Primary

  caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title

• G01R33/5612

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

• A61B5/055 Primary

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title