Method and magnetic resonance apparatus wherein limit values are observed when recording magnetic resonance data

Patent metadata

Field	Value
Publication number	US-10288710-B2
Application number	US-201715499170-A
Country	US
Kind code	B2
Filing date	Apr 27, 2017
Priority date	Apr 28, 2016
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

In a magnetic resonance (MR) apparatus and an operating method therefor, a sequence with which the MR data are to be recorded is created in or provided to a control computer of the MR apparatus. A maximum RF output and a maximum gradient performance of the scanner magnetic resonance apparatus during the performance of the sequence are determined by simulating or analyzing the performance of the sequence in the control computer, and it is verified whether the maximum RF output and/or the maximum gradient performance violate predetermined limit values. Execution of the sequence to record the MR data is performed only if the verification showed that the limit values are not violated.

First claim

The invention claimed is:

1. A method for operating a magnetic resonance (MR) apparatus comprising:
in a control computer of an MR apparatus comprising an MR data acquisition scanner, acquiring a data acquisition sequence that will be used to operate the MR data acquisition scanner to acquire MR data from a subject having an active implanted medical device therein, said data acquisition sequence comprising RF pulses that produce an RF output and gradient pulses that control entry of said MR data into a memory organized as k-space;
in said control computer, simulating or analyzing any part of said sequence that is less than all said sequence, in order to determine a maximum radio frequency (RF) output, and simulating or analyzing only gradient pulses in said sequence that cause entry of said MR data into a periphery of k-space in order to determine maximum gradient performance, that will occur in said MR data acquisition scanner during execution of said sequence;
in said control computer, verifying whether either of said maximum RF output and said maximum gradient performance violate predetermined limit values imposed by standards for conducting MR examinations of subjects with an active implanted medical device therein; and
from said control computer, emitting an output signal that causes said MR data acquisition sequence to be executed by said MR data acquisition scanner to acquire said MR data only if the verification showed that the limit values are not violated for both said RF output and said maximum gradient performance.

2. A method as claimed in claim 1 comprising, in said control computer, verifying whether either of the maximum RF output and the maximum gradient performance violate the predetermined limit values by executing at least one verification selected from the group consisting of verifying whether a maximum value of the RF output of the MR data acquisition scanner is larger than a first limit value for magnetic flux density during execution of said MR data acquisition sequence, verifying whether a temporal mean value of the RF output of the MR data acquisition scanner is larger than a second limit value for magnetic flux density during execution of said MR data acquisition sequence, verifying whether a maximum value of an amount of a temporal alteration of the gradient performance of the MR data acquisition scanner is larger than a first limit value for an alteration of magnetic flux density per time unit during execution of said MR data acquisition sequence, and verifying whether a temporal mean value of an amount of a temporal alteration of the gradient performance of the MR data acquisition scanner is larger than a second limit value for an alteration of magnetic flux density per time unit during execution of said MR data acquisition sequence.

3. A method as claimed in claim 1 comprising, in said control computer, if the limit values are violated, determining which of said limit values is violated and determining a percentage by which the determined limit value is violated.

4. A method as claimed in claim 1 comprising, in said control computer, if the limit values are violated, determining at least one parameter of said MR data acquisition sequence and a parameter value for each parameter that, when the MR data acquisition sequence is modified to give said at least one parameter said parameter value, the MR data acquisition sequence then does not violate the limit values.

5. A method as claimed in claim 4 comprising, in said control computer, determining said at least one parameter and said parameter value for each parameter by implementing a binary search comprising:
setting said at least one parameter to a value in a center of a still possible range of values;
simulating or analyzing whether the limit value corresponding to the modified parameter is violated by the modified sequence;
restricting the still possible range of values to half of said range, dependent on the result of said simulating or analyzing; and
cancelling said binary search if a predetermined cancellation criterion is not satisfied.

6. A method as claimed in claim 4 comprising selecting said at least one parameter from the group consisting of a flip angle of an RF pulse of said MR data acquisition sequence, a type of RF pulse in said MR data acquisition sequence, a repetition time with which said MR data acquisition sequence is repeated, a number of slices from which MR data are acquired in said MR data acquisition sequence, a thickness of a slice from which MR data are acquired in said MR data acquisition sequence, an interval between selected components of said MR data acquisition sequence, a slew rate of a gradient moment in said MR data acquisition sequence, and a resolution with which the MR data are acquired in said MR data acquisition sequence.

7. A method as claimed in claim 4 comprising:
at a display screen in communication with said control computer, displaying said at least one parameter with the determined parameter value thereof; and
changing said MR data acquisition sequence according to said at least one parameter with the determined parameter value, and not executing said MR data acquisition sequence to acquire MR data until confirmation from a user is received as an input into said control computer.

8. A method as claimed in claim 4 comprising determining a range of values for each of said at least one parameter, determining said at least one parameter and said parameter value therefore only from parameter values within said range in order to not violate the limit values.

9. A magnetic resonance (MR) apparatus comprising:
an MR data acquisition scanner comprising a basic field magnet, a gradient field system, at least one radio frequency (RF) antenna;
a control computer configured to acquire a data acquisition sequence that will be used to operate the MR data acquisition scanner to acquire MR data from a subject having an active implanted medical device therein, said data acquisition sequence comprising RF pulses that produce an RF output and gradient pulses that control entry of said MR data into a memory organized as k-space;
said control computer being configured to simulate or analyze any part of said sequence that is less than all said sequence, in order to determine a maximum radio frequency (RF) output, and to simulate or analyze only gradient pulses in said sequence that cause entry of said MR data into a periphery of k-space in order to determine maximum gradient performance, that will occur in said MR data acquisition scanner during execution of said sequence;
said control computer being configured to verify whether either of said maximum RF output and said maximum gradient performance violate predetermined limit values imposed by standards for conducting MR examinations of subjects with an active implanted medical device therein; and
said control computer being configured to emit an output signal that causes said MR data acquisition sequence to be executed by said MR data acquisition scanner to acquire said MR data only if the verification showed that the limit values are not violated for both said RF output and said maximum gradient performance.

10. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control computer of a magnetic resonance (MR) apparatus that comprises an MR data acquisition scanner, said programming instructions causing said control computer to:
acquire a data acquisition sequence that will be used to operate the MR data acquisition scanner to acquire MR data from a subject having an active implanted medical device therein, said data acquisition sequence comprising RF pulses that produce an R

Assignees

• Siemens Healthcare Gmbh

Inventors

• Bielmeier Wolfgang
• Brinker Gerhard
• Campagna Swen
• Demharter Nikolaus
• Erbe Bernd
• Gebhardt Matthias
• Nistler Juergen
• Paul Dominik
• Prinz Carsten
• Ruyters Gudrun
• Stoecker Stephan
• Vester Markus

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

• G01R33/385

  using gradient magnetic field coils · CPC title

• G01R33/36

  Electrical details, e.g. matching or coupling of the coil to the receiver · CPC title