Ascertaining an item of movement information describing a movement in an at least partially moved examination region

Patent metadata

Field	Value
Publication number	US-10564244-B2
Application number	US-201615367358-A
Country	US
Kind code	B2
Filing date	Dec 2, 2016
Priority date	Dec 3, 2015
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

A method is provided for ascertaining at least one item of movement information describing a sought movement as a partial movement of an overall movement in an at least partially moved examination region. In the method, at least one excitation signal having a first frequency band is output and receiving signals generated by the excitation signal are recorded with a receiving coil arrangement, (e.g., a receiving coil arrangement of a magnetic resonance device), having a plurality of receiving channels. The coils of the receiving coil arrangement are designed to record a receiving frequency band including the first frequency band, wherein for ascertaining the movement information the complex receiving signals of the receiving channels are combined at one instant according to a combination specification ascertained over a period by an analysis of the receiving signals that identifies at least one component of a movement that contributes to the sought movement.

First claim

The invention claimed is:

1. A method for ascertaining an item of movement information describing a sought movement as a partial movement of an overall movement in a moved examination region, the method comprising:
outputting an excitation signal having a first frequency band and a high-frequency signal having a second frequency band that does not overlap with the first frequency band;
recording receiving signals and a magnetic resonance signal as an overall signal, wherein the receiving signals are generated by the excitation signal with a receiving coil arrangement of a magnetic resonance device having a plurality of receiving channels, wherein the magnetic resonance signal is generated by the high-frequency signal, and wherein coils of the receiving coil arrangement are configured to record a receiving frequency band comprising the first frequency band and the second frequency band;
extracting complex receiving signals from the overall signal using a basic frequency of the receiving signals, wherein the complex receiving signals comprise scanning information having amplitudes and phases relating to sampling instants associated with a sampling period, and wherein a reference signal of the basic frequency is generated from the overall signal to extract the complex receiving signals; and
ascertaining the movement information describing the sought movement, wherein the complex receiving signals of the receiving channels are combined at one instant according to a combination specification ascertained over a period by an analysis of the complex receiving signals that identifies at least one component of a movement that contributes to the sought movement.

2. The method of in claim 1 , wherein the movement information is ascertained by a linear combination of the complex receiving signals.

3. The method of in claim 2 , wherein the movement information is ascertained as a principle component of a principle component analysis, an independent component of an independent component analysis, or both the principle component and the independent component.

4. The method of claim 3 , wherein the principle component or the independent component is selected by a selection criterion or is manually selected.

5. The method of claim 4 , wherein, with a periodic movement, the selection criterion comprises a bandpass filter that selects a frequency range of the periodic movement and/or ascertains a ratio of a signal energy within the frequency range to a signal energy outside of the frequency range.

6. The method of claim 5 , wherein the periodic movement is a heartbeat of a patient, breathing of the patient, or both the heartbeat and breathing of the patient.

7. The method of claim 4 , further comprising:
determining the combination specification in an optimization method that maximizes a correlation of the linear combination of the complex receiving signals with a measurement signal describing a periodic movement.

8. The method of claim 7 , wherein the measurement signal is ascertained from a navigator recording ascertained by magnetic resonance imaging during the period.

9. The method of claim 7 , wherein the combination specification is updated by way of analysis for at least one further period that is at least partly more current.

10. The method of claim 1 , wherein as pre-processing of the complex receiving signals, downsampling occurs, based on a frequency range of a periodic movement, and/or a normalization of the phases of the complex receiving signals to a reference phase of a reference receiving signal.

11. The method of claim 1 , wherein the item of movement information is based on periodic movements of a patient including a heartbeat and/or breathing of the patient, and the method further comprises:
ascertaining an additional item of movement information based on other movements of the patient.

12. The method of claim 1 , further comprising:
automatically evaluating the movement information and/or presenting the movement information in a display on a display device.

13. The method of claim 12 , wherein the presentation of the movement information is based on either or both of an amplitude or value of the combination of the complex receiving signals, and
wherein an updating period and/or a temporal display is/are configured to an image recording interval of a simultaneously used image recording device.

14. The method of claim 1 , wherein an item of cycle information describing an instant or section of a periodic movement cycle is ascertained during recording of an image with simultaneously used image recording device from an item of movement information based on an at least periodic movement, in particular a heartbeat or a breathing of a patient and/or the movement information during recording of the image and/or the cycle information is stored so as to be associated with the image and/or the image.

15. The method of claim 1 , wherein signal magnitudes of the overall signal averaged over all receiving channels are divided for pre-determined frequency intervals by a corresponding difference of the signal magnitudes over considered sampling instants of the sampling period and receiving channels, and the basic frequency is ascertained from results of division that exceed a threshold value.

16. The method of claim 15 , wherein the basic frequency is ascertained after pre-filtering with a window filter.

17. The method of claim 15 , wherein the corresponding difference is a variance.

18. The method of claim 15 , wherein the basic frequency is determined within a framework of an interpolation of the remaining results of division.

19. The method of claim 15 , wherein the basic frequency is determined within a framework of an interpolation by a first moment of the remaining results of division.

20. The method of claim 1 , wherein, for each receiving channel, the overall signal is multiplied by a complex conjugate of the reference signal and averaged over all sampling instants.

21. The method of claim 20 , wherein the complex receiving signal multiplied by the reference signal is subtracted from the overall signal to extract at least one further signal.

22. A magnetic resonance device comprising:
a receiving coil arrangement; and
a controller configured to:
output an excitation signal having a first frequency band and a high-frequency signal having a second frequency band that does not overlap with the first frequency band;
record receiving signals and a magnetic resonance signal as an overall signal, wherein the receiving signals are generated by the excitation signal with the receiving coil arrangement of the magnetic resonance device having a plurality of receiving channels, wherein the magnetic resonance signal is generated by the high-frequency signal, and wherein coils of the receiving coil arrangement are configured to record a receiving frequency band comprising the first frequency band and the second frequency band;
extract complex receiving signals from the overall signal using a basic frequency of the receiving signals, wherein, a reference signal of the basic frequency is generated from the overall signal to extract the complex receiving signals for a scanning instant associated with a sampling period, and for each receiving channel, the overall signal is multiplied by a complex conjugate of the reference signal and averaged over all sampling instants; and
ascertain movement information describing a sought movement, wherein the complex receiving signals of the receiving channels a

Assignees

• Fenchel Matthias
• Speier Peter
• Siemens Healthcare Gmbh

Inventors

• Fenchel Matthias
• Speier Peter

Classifications

• A61B5/055 Primary

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

• A61B5/7289

  Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition · CPC title

• G01R33/5676

  Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction · CPC title

• G01R33/34

  Constructional details, e.g. resonators {, specially adapted to MR} · CPC title

• G01R33/5673 Primary

  Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker · CPC title