Patent application EP20179903A (EP), filed 2020-06-15
Publication number: EP3926355A1
Title: ESTIMATION OF B0 INHOMOGENEITIES FOR IMPROVED ACQUISITION AND/OR RECONSTRUCTION OF MAGNETIC RESONANCE IMAGES
Abstract: [0001]    Disclosed herein is a medical system (100, 300, 500) comprising a memory (110) storing machine executable instructions (120) and a Bo field estimation module (126); and a computational system (106). Execution of the machine executable instructions causes the computational system to receive (200) an initial magnetic resonance image (122) that comprises a magnitude component and is descriptive of a first region (326) of interest of a subject (118). Execution of the machine executable instructions further causes the computational system to perform at least one iteration of the following: receive (202) subsequent k-space data (124) descriptive of a subsequent region of interest (328) of the subject; calculate (204) an estimated Bo field mapping (128) for the subsequent region of interest from the initial magnetic resonance image by inputting the initial magnetic resonance image into the Bo field estimation module; and reconstruct (206) a corrected magnetic resonance image (130) from the subsequent k-space data and the estimated Bo field mapping.
IPC codes: G01R  33/    24            A I
G01R  33/  3875            A I
G01R  33/    54            A I
G01R  33/   565            A I
G06N   3/    02            A I
Claims: number: 1
text: A medical system (100, 300, 500) comprising:
number: 2
text: The medical system of claim 1, wherein the medical system further comprises a magnetic resonance imaging system (302) configured for acquiring k-space data from an imaging zone (308), wherein the memory further contains first pulse sequence commands (330) configured for acquiring initial k-space data (332) from the first region of interest, wherein the memory further contains a set of second pulse sequence commands (334) each configured for acquiring the subsequent k-space data from the subsequent region of interest, wherein execution of the machine executable instructions further causes the computational system to:
number: 3
text: The medical system of claim 2, wherein the magnetic resonance imaging system comprises a main magnet (304) for generating a B<0> magnetic field in the imaging zone, wherein the magnetic resonance imaging system further comprises an adjustable B<0> magnetic field shim (322, 324) configured for shimming the B<0> magnetic field in the imaging zone,
wherein execution of the machine executable instructions further causes the computational system to perform the following before each acquisition of the subsequent k-space data:
number: 4
text: The medical system of claim 3, wherein the estimated B<0> field mapping is calculated (606) at least partially using the updated B<0> shim settings.
number: 5
text: The medical system of claim 3, 4, or 5, wherein execution of the machine executable instructions further causes the computational system to perform the following for the acquisition of the subsequent k-space data: receive (608) motion parameters (506) descriptive of motion of the subject during or after acquisition of subsequent k-space data; wherein the estimated B<0> field is calculated at least partially using the motion parameters.
number: 6
text: The medical system of claim 5, wherein the medical system further comprises a motion sensor system (502) configured for at least partially measuring the motion parameters, wherein execution of the machine executable instructions further causes the computational system to control the motion sensor system to measure the motion parameters.
number: 7
text: The medical system of claim 5 or 6, wherein execution of the machine executable instructions further causes the computational system to:
number: 8
text: The medical system of claim 5, 6, or 7, wherein the estimated B<0> field is calculated at least partially by any one of the following:
number: 9
text: The medical system of any one of claims 2 through 8, wherein the memory further contains a system model (512) configured for outputting time dependent data (514) descriptive of electromagnetic properties of the magnetic resonance imaging system in response to inputting the one of the set of second pulse sequence commands, wherein execution of the machine executable instructions further causes the computational system to calculate the time dependent data by inputting the subsequent pulse sequence commands into the system model, wherein the corrected magnetic resonance image is reconstructed from the subsequent k-space data, the estimated B<0> field mapping, and the time dependent data.
number: 10
text: The medical system of claim 9, wherein the time dependent data is descriptive of any one of the following: B<0> inhomogeneities caused by eddy currents, temperature dependent gradient magnetic field nonlinearities, time dependent gradient magnetic field nonlinearities, changes in magnetic resonance coil sensitivities, motion dependent B<1> inhomogeneities, static magnetic gradient field nonlinearities, concomitant magnetic field corrections, and combinations thereof.
number: 11
text: The medical system of any one of claims 2 through 10, wherein the one of the second pulse sequence commands is configured to acquire the subsequent k-spaced data according to any one of the following:
number: 12
text: The medical system of any one of the preceding claims, wherein the B<0> field estimation module is implemented as any one of the following:
number: 13
text: The medial system of any one of the preceding claims, wherein any one of the following:
number: 14
text: A computer program comprising machine executable instructions for execution by a computational system (106) controlling a medical system (100, 300, 500), wherein execution of the machine executable instructions causes the computational system to: receive (200) an initial magnetic resonance image (122) descriptive of a first region of interest (326) of a subject (118), wherein the initial magnetic resonance image comprises a magnitude component;
wherein execution of the machine executable instructions further causes the computational system to perform an iteration of the following at least once:
number: 15
text: A method of medical imaging, wherein the method comprises receiving (200) an initial magnetic resonance image (122) descriptive of a first region of interest (326) of a subject (118), wherein the initial magnetic resonance image comprises a magnitude component;
wherein the method comprises performing an iteration of the following at least once:
Office action: search_report, dated 2021-12-22
Rejection reasons: novelty_epc_54
Prior art cited: ref_id: - SHI: "Template-Based Field Map Prediction for Rapid Whole Brain Bo Shimming", MAGNETIC RESONANCE IN MEDICINE, vol. 80, 2018, pages 171 - 180
ref_type: npl
severity: background
ref_id: US2006220645A1
ref_type: patent
severity: background
ref_id: - JUNMIN LIU ET AL: "Method of B0 mapping with magnitude-based correction for bipolar two-point Dixon cardiac MRI", MAGNETIC RESONANCE IN MEDICINE, vol. 78, no. 5, 8 December 2016 (2016-12-08), US, pages 1862 - 1869, XP055478429, ISSN: 0740-3194, DOI: 10.1002/mrm.26569
ref_type: npl
severity: background
ref_id: US2006220645
ref_type: patent
severity: novelty_destroying
ref_id: - JUNMIN LIU ET AL, "Method of B0 mapping with magnitude-based correction for bipolar two-point Dixon cardiac MRI", MAGNETIC RESONANCE IN MEDICINE, US, (20161208), vol. 78, no. 5, doi:10.1002/mrm.26569, ISSN 0740-3194, pages 1862 - 1869, XP055478429 [X] 1,2,13-15 * sections "INTRODUCTION" and "METHODS";; figures 1,3,4 * [I] 3-12
ref_type: npl
severity: novelty_destroying
Final disposition: pending (2021-12-22)