# US 12,007,460 B2 · Actuating a magnetic resonance device with compensated Maxwell phase > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,007,460 B2 - Document ID: US12007460B2 - Status: Granted - Kind: B2 - Application number: 17/902,081 - Filed: 2022-09-02 - Published: 2023-03-09 - Granted: 2024-06-11 - Earliest claimed: 2021-09-03 - Assignees: Siemens Healthineers AG - Applicants: Siemens Healthcare GmbH - Inventors: Mario Zeller; Kun Zhou; Dominik Paul - Web page: https://patentgrep.com/patent/US12007460B2 ## CPC - G01R 33/56581: {due to Maxwell fields, i.e. concomitant fields} - G01R 33/543: {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)} - G01R 33/5618: {using both RF and gradient refocusing, e.g. GRASE} - G01R 33/288: {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} - G01R 33/4828: {Resolving the MR signals of different chemical species, e.g. water-fat imaging} - G01R 33/5617: {using RF refocusing, e.g. RARE} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method for actuating a magnetic resonance device according to an MR control sequence, wherein the MR control sequence includes a bipolar gradient pulse between an excitation pulse and a first refocusing pulse, and the bipolar gradient pulse induces a defined Maxwell phase and generates a dephasing gradient moment for a readout gradient. ## Claims ### Claim 1 A method for actuating a magnetic resonance (MR) device according to an MR control sequence comprising: at least one excitation pulse followed by at least two consecutive refocusing pulses, wherein, between exactly two of the at least two consecutive refocusing pulses, all magnetic field gradients acting on a readout axis of the readout gradient induce a first Maxwell phase and at least one readout gradient is provided; and a bipolar gradient pulse having a first part and a second part of opposite polarity arranged between the excitation pulse and a first of the at least two consecutive refocusing pulses, wherein a Maxwell phase induced by the bipolar gradient pulse corresponds to between 40% and 60% of the first Maxwell phase, a gradient moment of the bipolar gradient pulse corresponds to a dephasing gradient moment for the readout gradient, and a duration of the bipolar gradient pulse corresponds at most to a first time interval between the excitation pulse and a first of the at least two consecutive refocusing pulses. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the first part of the bipolar gradient pulse has the same polarity as the readout gradient. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein the MR control sequence is embodied as a DIXON sequence or as a turbo-gradient-spin-echo sequence. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein at least two readout gradients are provided between exactly two of the at least two consecutive refocusing pulses and the dephasing gradient moment for the readout gradient only takes account of a first readout gradient of the at least two readout gradients. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein only the bipolar gradient pulse is provided between the excitation pulse and the first of the at least two consecutive refocusing pulses on the readout axis of the readout gradient. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein the bipolar gradient pulse has a duration greater than 50% and less than 95% of the first time interval. ### Claim 7 (depends on 1) The method as claimed in claim 1, further comprising providing the MR control sequence by: providing the excitation pulse followed by the at least two consecutive refocusing pulses and the at least one readout gradient; providing an initial dephasing gradient corresponding to the readout gradient having the dephasing gradient moment; and transforming the initial dephasing gradient to the first part of the bipolar gradient pulse, comprising changing an amplitude of the initial dephasing gradient and/or changing a duration of the initial dephasing gradient, taking account of the first time interval, under a condition that a Maxwell phase induced by the first part of the bipolar gradient pulse corresponds to a Maxwell phase induced by the initial dephasing gradient. ### Claim 8 (depends on 7) The method as claimed in claim 7, wherein the transformation takes place under a condition that the gradient moment of the first part of the bipolar gradient pulse corresponds to the dephasing gradient moment minus the gradient moment of the second part of the bipolar gradient pulse. ### Claim 9 (depends on 7) The method as claimed in claim 7, further comprising: providing the first Maxwell phase; and defining the second part of the bipolar gradient pulse, wherein the Maxwell phase induced by the second part of the bipolar gradient pulse corresponds to half the first Maxwell phase minus the Maxwell phase of the initial dephasing gradient. ### Claim 10 (depends on 9) The method as claimed in claim 9, wherein a definition of the second part of the bipolar gradient pulse takes place under the condition that the duration of the second part of the bipolar gradient pulse corresponds to between 50% and 95% of the time interval between the initial dephasing gradient and a first of the at least two consecutive refocusing pulses. ### Claim 11 (depends on 1) A magnetic resonance device with a control unit comprising an actuating unit configured to execute a method for actuating the magnetic resonance device as claimed in claim 1. ### Claim 12 (depends on 1) A non-transitory electronically readable data carrier on which a program is stored, which is embodied such that the program performs the method for actuating a magnetic resonance device as claimed in claim 1 when the data carrier is used in an actuating unit.