# US 12,181,549 B2 · Method for determining a B0 map > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,549 B2 - Document ID: US12181549B2 - Status: Granted - Kind: B2 - Application number: 18/073,547 - Filed: 2022-12-01 - Published: 2023-06-08 - Granted: 2024-12-31 - Earliest claimed: 2021-12-02 - Assignees: Siemens Healthineers AG - Applicants: Siemens Healthcare GmbH - Inventors: David Grodzki; Dieter Ritter; Armin Nagel; Christian Eisen - Web page: https://patentgrep.com/patent/US12181549B2 ## CPC - G01R 33/243: {Spatial mapping of the polarizing magnetic field} - G01R 33/443: {Assessment of an electric or a magnetic field, e.g. spatial mapping, determination of a B0 drift or dosimetry} - G01R 33/56563: {caused by a distortion of the main magnetic field B0, e.g. temporal variation of the magnitude or spatial inhomogeneity of B0 (G01R33/56509, G01R33/56518, G01R33/56536 take precedence)} - G01R 33/3875: using correction coil assemblies, e.g. active shimming - G01R 33/5608: {Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method for determining a B0 map for, for example, performing an imaging magnetic resonance measurement using a magnetic resonance apparatus, includes measuring an original magnetic field distribution in a measurement volume of the magnetic resonance apparatus, and computing a final B0 map that describes a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting a shim state. The magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting the shim state differs from the original magnetic field distribution. ## Claims ### Claim 1 A method for computing a final B0 map for performing an imaging magnetic resonance measurement using a magnetic resonance apparatus, the method comprising: measuring an original magnetic field distribution in a measurement volume of the magnetic resonance apparatus; and computing a final B0 map that describes a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting a shim state, wherein the measured original magnetic field distribution is the only measured data included in the computing of the final B0 map, and wherein a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting the shim state differs from the original magnetic field distribution. ### Claim 2 (depends on 1) The method of claim 1, further comprising setting the shim state based on the original magnetic field distribution. ### Claim 3 (depends on 2) The method of claim 2, wherein setting the shim state based on the original magnetic field distribution comprises setting the shim state based on a first B0 map that is determined from the original magnetic field distribution. ### Claim 4 (depends on 2) The method of claim 2, wherein setting the shim state comprises determining electric shim currents for at least one magnetic field coil of the magnetic resonance apparatus based on the original magnetic field distribution, wherein the computing of the final B0 map is carried out based on the original magnetic field distribution and the determined electric shim currents for the at least one magnetic field coil of the magnetic resonance apparatus. ### Claim 5 (depends on 2) The method of claim 2, wherein setting the shim state comprises determining electric shim currents for at least one magnetic field coil of the magnetic resonance apparatus, and wherein computing the final B0 map comprises: computing a provisional B0 field based on the original magnetic field distribution and the determined electric shim currents for the at least one magnetic field coil; receiving the provisional B0 map as input data of a trained function; applying the trained function to the input data; and outputting the final B0 map as output data of the further trained function. ### Claim 6 (depends on 5) The method of claim 5, wherein computing the provisional B0 map comprises: computing an additional magnetic field distribution brought about in the measurement volume of the magnetic resonance apparatus by the determined electric shim currents; and adding the additional magnetic field distribution to the original magnetic field distribution in the measurement volume of the magnetic resonance apparatus. ### Claim 7 (depends on 4) The method of claim 4, wherein the computing of the final B0 map is carried out based on a first B0 map that is determined from the original magnetic field distribution. ### Claim 8 (depends on 4) The method as claimed in claim 4, further comprising computing an additional magnetic field distribution brought about in the measurement volume of the magnetic resonance apparatus by the determined shim currents, wherein the additional magnetic field distribution is added to the original magnetic field distribution in the measurement volume of the magnetic resonance apparatus. ### Claim 9 (depends on 1) The method of claim 1, further comprising computing control signals using the final B0 map, the control signals being for transmission of a radio frequency (RF) pulse by at least one transmit antenna of the magnetic resonance apparatus. ### Claim 10 (depends on 9) The method of claim 9, wherein the at least one transmit antenna comprises a plurality of transmit antennas. ### Claim 11 (depends on 1) The method of claim 1, wherein computing the final B0 map comprises: receiving the original magnetic field distribution or a B0 map as input data of a trained function; applying the trained function to the input data; and outputting the final B0 map as output data of the trained function. ### Claim 12 (depends on 11) The method of claim 11, wherein receiving the original magnetic field distribution or the B0 map as the input data of the trained function comprises receiving a first B0 map that is determined from the original magnetic field distribution as the input data of the trained function. ### Claim 13 (depends on 1) The method of claim 1, further comprising performing an imaging magnetic resonance measurement using the magnetic resonance apparatus and the final B0 map. ### Claim 14 A system control unit for a magnetic resonance apparatus, the system control unit comprising: a processor configured to: receive an original magnetic field distribution in a measurement volume of the magnetic resonance apparatus; compute a final B0 map that describes a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting a shim state, wherein the received original magnetic field distribution is the only measured data included in the computation of the final B0 map, and wherein a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting the shim state differs from the original magnetic field distribution. ### Claim 15 A magnetic resonance apparatus comprising: a system control unit comprising: a processor configured to: measure an original magnetic field distribution in a measurement volume of the magnetic resonance apparatus; set a shim state in the measurement volume of the magnetic resonance apparatus based on the measured original magnetic field distribution, wherein a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting the shim state differs from the original magnetic field distribution; and compute a final B0 map that describes a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by the setting of a shim state, wherein the measured original magnetic field distribution is the only measured data included in the computation of the final B0 map. ### Claim 16 (depends on 15) The magnetic resonance apparatus of claim 15, wherein the magnetic resonance apparatus is configured to perform an imaging magnetic resonance measurement using the final B0 map. ### Claim 17 In a non-transitory computer-readable storage medium that stores instructions executable by a system control unit of a magnetic resonance apparatus to compute a final B0 map for performing an imaging magnetic resonance measurement using a magnetic resonance apparatus, the instructions comprising: measuring an original magnetic field distribution in a measurement volume of the magnetic resonance apparatus; and computing a final B0 map that describes a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting a shim state, wherein the measured original magnetic field distribution is the only measured data included in the computing of the final B0 map, and wherein a magnetic field distribution produced in the measurement volume of the magnetic resonance apparatus by setting the shim state differs from the original magnetic field distribution. ### Claim 18 (depends on 17) The non-transitory computer-readable storage medium of claim 17, wherein the instructions further comprise setting the shim state based on the original magnetic field distribution.