Frequency monitoring of gradient pulses in magnetic resonance imaging

Patent metadata

Field	Value
Publication number	US-10042019-B2
Application number	US-201514748780-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jun 24, 2014
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

Different properties of a frequency monitor of a magnetic resonance imaging system are adaptively adjusted, for example as a function of a user input or a temperature. The frequency monitor monitors a system variable indicative of a mechanical flux of force in a gradient system of the magnetic resonance imaging system. Selective aborting of the performance of a magnetic resonance imaging measuring sequence takes place.

First claim

I claim as my invention:

1. A magnetic resonance (MR) apparatus comprising:
an MR scanner comprising a gradient coil system that, when operated according to an MR data acquisition sequence, produces a mechanical magnetic flux in said MR scanner;
a control computer configured to operate said MR scanner according to said MR data acquisition sequence in which said mechanical magnetic flux is produced in the MR scanner by the gradient system of the MR scanner;
a user interface that enters a signal representing a user input into the control computer for a user-selected factor that is involved in acquisition of said MR data by said MR scanner;
said control computer being configured to automatically select a threshold value dependent on said signal, said threshold value designating an amplitude of said mechanical magnetic flux in a frequency band;
said control computer being configured to operate said MR scanner according to said MR data acquisition sequence to acquire MR data from an examination object in said MR scanner, including application of a temporal sequence of gradient pulses along at least one gradient axis;
a system variable monitor configured to monitor, during operation of said MR scanner according to said MR data acquisition sequence, a system variable of said MR scanner that is indicative of said mechanical magnetic flux in said frequency band;
said control computer being configured to compare the detected system variable with said threshold value to obtain a comparison result;
said control computer being configured to make an evaluation, dependent on said comparison result, as to whether operation of the MR scanner in the MR data acquisition sequence should continue or be aborted;
if said operation of said MR scanner in said MR data acquisition sequence is to be aborted, said control computer being configured to generate an abort signal and to provide said abort signal to said MR scanner, and thereby stop operation of said MR scanner in said MR data acquisition sequence; and
if said operation of said MR scanner is not aborted, said control computer being configured to make the MR data acquired from the examination object with said MR data acquisition sequence available in electronic form as a data file at an output of said control computer.

2. A method for acquiring magnetic resonance (MR) data, comprising:
receiving an input into a control computer configured to operate an MR scanner according to an MR data acquisition sequence in which mechanical magnetic flux is produced in the MR scanner by a gradient system of the MR scanner that is operated according to said MR data acquisition sequence, said input to the control computer designating a user-selected factor that is involved in acquisition of said MR data by said MR scanner;
executing a threshold value selection in said control computer, in order to automatically select a threshold value dependent on said input, said threshold value designating an amplitude of said mechanical magnetic flux in a frequency band;
using said control computer to operate said MR scanner according to said MR data acquisition sequence in order to acquire MR data from an examination object in said MR scanner, including application of a temporal sequence of gradient pulses along at least one gradient axis;
during operation of said MR scanner according to said MR data acquisition sequence, monitoring a system variable of said MR scanner that is indicative of said mechanical magnetic flux in said frequency band;
executing a comparison in said control computer of the detected system variable with said threshold value in order to obtain a comparison result;
executing an evaluation in said control computer dependent on said comparison result, as to whether operation of the MR scanner in the MR data acquisition sequence should continue or be aborted;
if said operation of said MR scanner in the MR data acquisition sequence is to be aborted, generating an abort signal in said control computer and providing said abort signal to said MR scanner, and thereby stopping operation of said MR scanner in said MR data acquisition sequence; and
if said operation of said MR scanner is not aborted, making the MR data acquired from the examination object with said MR data acquisition sequence available in electronic form as a data file at an output of said control computer.

3. A method as claimed in claim 2 comprising, in said control computer, selecting a bandwidth of said frequency band dependent on said signal.

4. A method as claimed in claim 3 comprising determining said threshold value to describe said amplitude in said frequency band as a function of a frequency with a predetermined frequency response, and detecting said system variable in said frequency band as a function of frequency, and comparing said threshold value to the detected system variable as a function of frequency.

5. A method as claimed in claim 4 wherein the frequency response of the threshold value in the frequency band is described by a function that is symmetrical with respect to a center of said frequency band.

6. A method as claimed in claim 2 comprising detecting said system variable by at least one of a Fourier transformation in said control computer of a time characteristic of a current intensity in at least one gradient coil of the MR scanner, and Fourier transformation in said control computer of a time characteristic of a measured magnetic field of a gradient pulse, measured with a magnetic field sensor in said MR scanner.

7. A method as claimed in claim 6 comprising determining said system variable as an integration over time of either of the Fourier transformed time characteristics.

8. A method as claimed in claim 2 wherein said user input is selected from the group consisting of noise development, heat development, energy consumption, abort tolerance, and equipment wear.

9. A method as claimed in claim 2 comprising selecting a temperature response of said frequency band as a function of said signal.

10. A method for acquiring magnetic resonance (MR) data, comprising:
receiving an input into a control computer configured to operate an MR scanner according to an MR data acquisition sequence in which mechanical magnetic flux is produced in the MR scanner by a gradient system of the MR scanner that is operated according to said MR data acquisition sequence, said input being indicative of a temperature in a region of the gradient system involved in acquisition of said MR data by said MR scanner;
executing a threshold value selection in said control computer, in order to automatically select a frequency band and a threshold value dependent on said input, said threshold value designating an amplitude of said mechanical magnetic flux in said frequency band;
using said control computer to operate said MR scanner according to said MR data acquisition sequence in order to acquire MR data from an examination object in said MR scanner, including application of a temporal sequence of gradient pulses along at least one gradient axis;
during operation of said MR scanner according to said MR data acquisition sequence, monitoring a system variable of said MR scanner that is indicative of said mechanical magnetic flux in said frequency band;
executing a comparison in said control computer of the detected system variable with said threshold value to obtain a comparison result;
said control computer being configured to make an evaluation, dependent on said comparison result, as to whether operation of the MR scanner in the MR data acquisition sequence should continue or be aborted;
if said operation of said MR scanner in the MR data acquisition sequence is to be aborted, generating an abort signal in said control

Assignees

• Siemens Ag

Inventors

• Grodzki David

Classifications

• G01R33/3607

  RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal · CPC title

• G01R33/3854 Primary

  means for active and/or passive vibration damping or acoustical noise suppression in gradient magnet coil systems · CPC title

• G01R33/543

  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

• A61B2560/0266

  for monitoring or limiting apparatus function · CPC title

• A61B5/055

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