Magnetic resonance facility operation

Patent metadata

Field	Value
Publication number	US-11998309-B2
Application number	US-202318129221-A
Country	US
Kind code	B2
Filing date	Mar 31, 2023
Priority date	Apr 1, 2022
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

A method for operating a magnetic resonance facility in which a measurement gradient pulse is used to record magnetic resonance signals for sampling k-space along a trajectory section. The recorded magnetic resonance signals are assigned to k-space points using a shape function describing the time profile of the measurement gradient pulse. To correct deviations of the real time profile of the measurement gradient pulse from an assumed target profile, a first correction measurement is performed to ascertain first magnetic resonance signals of the trajectory section. A second correction measurement is then performed using a reference sampling pattern or a reference gradient pulse with fewer deviations from an assigned reference target profile. If a deviation criterion is met, a correction function for the shape function is ascertained by aligning the first and second magnetic resonance signals to one another, providing correction information to be used in an imaging measurement.

First claim

The invention claimed is:

1. A method for operating a magnetic resonance device in which a measurement gradient pulse is used to record magnetic resonance signals for sampling k-space along a trajectory section, wherein the measurement of the magnetic resonance signals takes place at recording times forming a measurement sampling pattern in a recording time window during the measurement gradient pulse and a shape function describing a time profile of the measurement gradient pulse is used to assign magnetic resonance signals to k-space points, wherein, in order to ascertain correction information relating to deviations of a real time profile of the measurement gradient pulse from an assumed target profile of the measurement gradient pulse in the recording time window to be used in an imaging measurement during an ascertaining process, the method comprises:
the magnetic resonance device measuring a first correction to ascertain first magnetic resonance signals of the trajectory section by applying the measurement sampling pattern to the measurement gradient pulse under predetermined measurement conditions;
the magnetic resonance device measuring a second correction to ascertain second magnetic resonance signals of the trajectory section under the predetermined measurement conditions using a reference sampling pattern at gradient conditions of the measurement gradient pulse and/or a reference gradient pulse for which fewer deviations from an assigned reference target profile are expected; and
when a deviation criterion comparing the first and second magnetic resonance signals is satisfied, a correction unit of a control device of the magnetic resonance device ascertaining a correction function for the shape function as correction information by aligning the first and the second magnetic resonance signals to one another to improve a quality of magnetic resonance image data produced by the magnetic resonance device.

2. A magnetic resonance device comprising:
a control device operable to perform a method for operating a magnetic resonance device in which a measurement gradient pulse is used to record magnetic resonance signals for sampling k-space along a trajectory section, wherein the measurement of the magnetic resonance signals takes place at recording times forming a measurement sampling pattern in a recording time window during the measurement gradient pulse and a shape function describing a time profile of the measurement gradient pulse is used to assign magnetic resonance signals to k-space points, wherein, in order to ascertain correction information relating to deviations of a real time profile of the measurement gradient pulse from an assumed target profile of the measurement gradient pulse in the recording time window to be used in an imaging measurement during an ascertaining process,
wherein the magnetic resonance device is operable to measure a first correction to ascertain first magnetic resonance signals of the trajectory section by applying the measurement sampling pattern to the measurement gradient pulse under predetermined measurement conditions, and
wherein the magnetic resonance device is operable to measure a second correction to ascertain second magnetic resonance signals of the trajectory section under the predetermined measurement conditions using a reference sampling pattern at gradient conditions of the measurement gradient pulse and/or a reference gradient pulse for which fewer deviations from an assigned reference target profile are expected; and
a correction unit operable to, when a deviation criterion comparing the first and second magnetic resonance signals is satisfied, ascertain a correction function for the shape function as correction information by aligning the first and the second magnetic resonance signals to one another to improve a quality of magnetic resonance image data produced by the magnetic resonance device.

3. A non-transitory electronically readable data carrier on which a computer program is stored, and when executed on a control device of a magnetic resonance device, performs a method for operating a magnetic resonance device in which a measurement gradient pulse is used to record magnetic resonance signals for sampling k-space along a trajectory section, wherein the measurement of the magnetic resonance signals takes place at recording times forming a measurement sampling pattern in a recording time window during the measurement gradient pulse and a shape function describing a time profile of the measurement gradient pulse is used to assign magnetic resonance signals to k-space points, wherein, in order to ascertain correction information relating to deviations of a real time profile of the measurement gradient pulse from an assumed target profile of the measurement gradient pulse in the recording time window to be used in an imaging measurement during an ascertaining process, the method comprises:
measuring a first correction to ascertain first magnetic resonance signals of the trajectory section by applying the measurement sampling pattern to the measurement gradient pulse under predetermined measurement conditions;
measuring a second correction to ascertain second magnetic resonance signals of the trajectory section under the predetermined measurement conditions using a reference sampling pattern at gradient conditions of the measurement gradient pulse and/or a reference gradient pulse for which fewer deviations from an assigned reference target profile are expected; and
when a deviation criterion comparing the first and second magnetic resonance signals is satisfied, ascertaining a correction function for the shape function as correction information by aligning the first and the second magnetic resonance signals to one another to improve a quality of magnetic resonance image data produced by the magnetic resonance device.

4. The method as claimed in claim 1 , wherein the recording time window of the reference sampling pattern lies entirely within a gradient plateau, and spaced apart from a beginning of the gradient plateau by at least one predetermined delay time.

5. The method as claimed in claim 1 , further comprising:
selecting the reference sampling pattern describing Cartesian sampling.

6. The method as claimed in claim 5 , wherein, in case of a measurement sampling pattern describing non-Cartesian sampling, the method comprises:
converting the first magnetic resonance signals to the recording times of the reference sampling pattern before an evaluation of the deviation criterion and/or the alignment.

7. The method as claimed in claim 1 , wherein the measurement sampling pattern comprises sampling during at least one ramp of a trapezoidal measurement gradient pulse and/or at a beginning of a plateau of the trapezoidal measurement gradient pulse and/or the measurement gradient pulse has a sinusoidal shape and/or the measurement gradient pulse is applied for spiral imaging.

8. The method as claimed in claim 1 , wherein the first and the second correction measurement follow one another directly and/or at least one prephasing gradient pulse ( 13 ) is used, meaning that the trajectory section is at least partially swept during the recording time window ( 10 , 12 ) of the respective sampling pattern in the correction measurements.

9. The method as claimed in claim 1 , further comprising:
specifying at least one predetermined time interval, in which stronger deviations than in other time sections of the recording time window are expected, wherein, in at least one of the at least one first and second correction measurement, passage through a k-space center is positioned in at least one of the at least one predetermined time interval.

10. The method as claimed in claim 9

Assignees

• Siemens Healthcare Gmbh
• Siemens Healthineers Ag

Inventors

• Zeller Mario
• Köhler Michael
• Paul Dominik

Classifications

• A61B5/055 Primary

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

• G06T2207/10088

  Magnetic resonance imaging [MRI] · CPC title

• G01R33/54 Primary

  Signal processing systems, e.g. using pulse sequences {; Generation or control of pulse sequences; Operator console} · CPC title

• G01R33/56518 Primary

  due to eddy currents, e.g. caused by switching of the gradient magnetic field · CPC title

• G01R33/58

  Calibration of imaging systems, e.g. using test probes {, Phantoms; Calibration objects or fiducial markers such as active or passive RF coils surrounding an MR active material} · CPC title