Magnetic resonance apparatus and method for the operation thereof

Patent metadata

Field	Value
Publication number	US-2016169997-A1
Application number	US-201514970941-A
Country	US
Kind code	A1
Filing date	Dec 16, 2015
Priority date	Dec 16, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

In a magnetic resonance facility and operating method for acquiring image data of a patient in a manner defined by acquisition parameters, the acquisition of the image data is preceded by the performance of at least one alignment operation for adjusting operating parameters of the magnetic resonance facility that influence acquisition conditions for the current patient. At least one result data item describing the result of the alignment used for an at least partially automatic determination of at least one acquisition parameter not relating to the pulse shape of a radio-frequency pulse to be used during the acquisition.

First claim

We claim as our invention:

1 . A method for operating a magnetic resonance apparatus comprising a magnetic resonance scanner comprising a radio-frequency antenna and a computer configured to operate the magnetic resonance scanner to acquire diagnostic magnetic resonance data from a subject by executing a magnetic resonance data acquisition sequence that includes radiation of a radio-frequency pulse, having a pulse shape, from said radio-frequency antenna, said method comprising:
prior to operating said magnetic resonance scanner to acquire said diagnostic magnetic resonance data from the subject, operating said magnetic resonance scanner with said computer in an alignment procedure wherein operating parameters of said magnetic resonance scanner are adjusted that influence acquisition conditions for acquiring said diagnostic magnetic resonance data from the subject, and thereby obtaining at least one alignment result data item that describes a result from said alignment procedure; and via said computer, at least partially automatically determining at least one acquisition parameter, that does not relate to said pulse shape of said radio-frequency pulse, for operating said magnetic resonance scanner during the acquisition of said diagnostic magnetic resonance data from the subject, and making an electronic representation of said at least one acquisition parameter not relating to said pulse shape available from said computer.

2 . A method as claimed in claim 1 wherein said magnetic resonance scanner comprises a basic field magnet that generates as a basic magnetic field during said acquisition of diagnostic magnetic resonance data from the subject, and wherein said radio-frequency pulse has a radio-frequency field associated therewith, and wherein said method comprises, in said alignment procedure, performing shimming of at least one of said basic magnetic field and said radio-frequency field.

3 . A method as claimed in claim 2 comprising, following said shimming, generating a field map, as said at least one alignment result data item, of said at least one of said basic magnetic field and said radio-frequency field that has been shimmed.

4 . A method as claimed in claim 1 comprising providing said computer with patient-specific input parameters that are specific to said subject, and, in said computer, using said patient-specific input parameters together with said at least one alignment result data item to determine said at least one acquisition parameter.

5 . A method as claimed in claim 4 comprising selecting said patient-specific input parameter as an electronic designation of a parameter selected from the group consisting of a permitted electromagnetic exposure of the subject, an ability or willingness of the subject to cooperate with the acquisition of said diagnostic magnetic resonance data, a movement of the subject that is expected to occur during the acquisition of said diagnostic magnetic resonance data, physiological information relating to breathing activity of the subject, physiological information relating to the heartbeat of the subject, and an image data record acquired from the subject.

6 . A method as claimed in claim 4 wherein said patient-specific input parameter is an image data record of the subject, selected from the group consisting of an image data record acquired from the subject using said magnetic resonance scanner, an image data record acquired from the subject using the magnetic resonance scanner prior to said alignment procedure, an image data record acquired from the subject of a localizer scan, and an image data record acquired from the subject using a magnetic resonance scanner other than said magnetic resonance scanner.

7 . A method as claimed in claim 1 comprising determining said at least one acquisition parameter as a function of said at least one alignment result data item by executing an optimization algorithm in said computer, said optimization algorithm comprising a target function that systematically seeks to achieve at least one optimization target.

8 . A method as claimed in claim 7 wherein said optimization target is selected from the group consisting of a shortest possible acquisition time for acquiring said diagnostic magnetic resonance data from the subject, a lowest possible electromagnetic exposure of the subject during the acquisition of said diagnostic magnetic resonance data from the subject, a global specific absorption rate (SAR) value, a local SAR value, a highest possible image quality of an image produced from the diagnostic magnetic resonance data acquired from the subject, and a highest possible contrast in an image of the subject generated from said diagnostic magnetic resonance data.

9 . A method as claimed in claim 7 comprising, in said optimization algorithm, setting at least one boundary condition selected from the group consisting of a maximum electromagnetic exposure that is permitted for the subject, and a restriction in hardware or operation of said magnetic resonance scanner that is dependent on a maximum electromagnetic exposure that is permitted for the subject.

10 . A method as claimed in claim 7 comprising executing said optimization algorithm using the Bloch equations to obtain a value for said optimization target, also using predetermined acquisition parameters provided to said computer.

11 . A method as claimed in claim 7 comprising executing said optimization algorithm to permit a predetermined degree of deviation from said optimization target, and terminating said optimization algorithm when said optimization target, calculated by executing said optimization algorithm, is within said predetermined degree of deviation.

12 . A method as claimed in claim 11 wherein said permitted degree of deviation is selected from the group consisting of a permitted flip angle deviation, a permitted slice curvature, a permitted deviation from a predetermined slice profile, a permitted distortion of a basic magnetic field generated by said magnetic resonance scanner, a permitted deviation in a quality of image data generated from said diagnostic magnetic resonance data, a permitted signal dephasing that occurs during the acquisition of said diagnostic magnetic resonance data, and a permitted deviation from a contrast in an image of the subject generated from said diagnostic magnetic resonance data.

13 . A method as claimed in claim 1 comprising, from said computer, accessing a database and using information from said database, together with said at least one alignment result data item, to determine said at least one acquisition parameter.

14 . A method as claimed in claim 13 wherein said database comprises information acquired from a population of a plurality of subjects each having a set of acquisition parameters respectively associated therewith in said database, and wherein said computer implements an empirical optimization algorithm based on said information access from said database, together with said at least one alignment result data item, to determine said at least one acquisition parameter.

15 . A method as claimed in claim 13 comprising positioning said subject in said magnetic resonance scanner for acquiring said diagnostic magnetic resonance data and, after positioning said subject in the magnetic resonance scanner, acquiring a comparison data record from the subject in the magnetic resonance scanner and accessing, from said database, a database data record of the subject that is stored in the database together with associated acquisition parameters and, in said computer, comparing said comparison data record of the subject with

Assignees

• Siemens Ag

Inventors

• Fautz Hans-Peter
• Paul Dominik

Classifications

• G01R33/565

  Correction of image distortions, e.g. due to magnetic field inhomogeneities · CPC title

• 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

• G01R33/567

  gated by physiological signals {, i.e. synchronization of acquired MR data with periodical motion of an object of interest, e.g. monitoring or triggering system for cardiac or respiratory gating} · CPC title

• G01R33/288

  Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room · CPC title