A method, electromagnet device, and system for reducing a higher order term of a concomitant field in an imaging magnetic field during magnetic resonance imaging is described. The electromagnet system has a first shim coil configured to be driven to generate a first compensation magnetic field during imaging according to a first second-order compensation term, the first compensation magnetic field having a similar amplitude but opposite direction as that of a first second-order concomitant magnetic field.

Embodiments of the present application provide a magnetic resonance system and a shimming method and an imaging method thereof. The shimming method comprises: performing a scout scan on a subject to be examined, and obtaining phase data of a plurality of slice positions; determining three-dimensional space static magnetic field information according to the phase data of the plurality of slice positions; and determining a shimming value of a slice in a region of interest according to the three-dimensional space static magnetic field information.

Object specific in-homogeneities in an MRI system are corrected. Prescan information available at the MR imaging system is determined. The prescan information includes at least object specific information of an object located in the MR imaging system from which an MR image is to be generated. The prescan information does not include a B1 map of the MRI system with the object being present in the MR imaging system. The prescan information is applied to a trained machine learning module provided at the MRI system. The trained machine learning module determines and generates shimming information as output. The shimming information is applied to a shimming module of the MR imaging system, wherein the shimming module uses the shimming information to generate a corrected magnetic field B0.

Object specific in-homogeneities in an MRI system are corrected. Prescan information available at the MR imaging system is determined. The prescan information includes at least object specific information of an object located in the MR imaging system from which an MR image is to be generated. The prescan information does not include a B1 map of the MRI system with the object being present in the MR imaging system. The prescan information is applied to a trained machine learning module provided at the MRI system. The trained machine learning module determines and generates shimming information as output. The shimming information is applied to a shimming module of the MR imaging system, wherein the shimming module uses the shimming information to generate a corrected magnetic field B0.

Systems and methods involving: a housing having a bore in which a subject to be imaged is placed; a main magnet configured to generate a volume of magnetic field within the bore, the volume of magnetic field having inhomogeneity below a defined threshold; gradient coils configured to linearly vary the volume of magnetic field as a function of spatial location; pulse-generating coils configured to generate and apply radio frequency (RF) pulses to the volume of magnetic field in sequence to scan the portion of the subject; shim gradient coils configured to perturb a spatial distribution of the linearly varying volume of magnetic field; and a control unit configured to operate the gradient coils, pulse-generating coils, and shim gradient coils such that only the user-defined region within the volume of magnetic field is imaged.

Systems and methods involving: a housing having a bore in which a subject to be imaged is placed; a main magnet configured to generate a volume of magnetic field within the bore, the volume of magnetic field having inhomogeneity below a defined threshold; gradient coils configured to linearly vary the volume of magnetic field as a function of spatial location; pulse-generating coils configured to generate and apply radio frequency (RF) pulses to the volume of magnetic field in sequence to scan the portion of the subject; shim gradient coils configured to perturb a spatial distribution of the linearly varying volume of magnetic field; and a control unit configured to operate the gradient coils, pulse-generating coils, and shim gradient coils such that only the user-defined region within the volume of magnetic field is imaged.

The present invention provides a method for compensation of periodic B.sub.0 modulations from a periodic motion of a cold head (212) of a main magnet (114) of a magnetic resonance (MR) imaging system (110), whereby main windings (200) of the main magnet (114) are cooled to superconductivity by the cold head (212), which exerts a repetitive motion, the method comprising the steps of measuring a periodic occurrence of spatial field components of the B-field based on a motion of the cold head (212) as a function of time, performing a sensor measurement of a periodic, auxiliary parameter of the MR imaging system (110), which is not the periodic occurrence of spatial field components, synchronizing the periodic occurrence of spatial field components of the B-field with the measured periodic, auxiliary parameter of the MR imaging system (110), and triggering based on the measured periodic sensor measurement of the MR imaging system (110) a periodic application of compensation signals to compensate the periodic occurrence of spatial field components of the B-field based on a motion of the cold head (212). Furthermore, the present invention provides a MR imaging system (110) for providing an image representation of a region of interest (142) of a subject of interest (120) positioned in an examination space (116) of the MR imaging system (110), wherein the MR imaging system (110) is adapted to perform the above method.

The present invention provides a method for compensation of periodic B.sub.0 modulations from a periodic motion of a cold head (212) of a main magnet (114) of a magnetic resonance (MR) imaging system (110), whereby main windings (200) of the main magnet (114) are cooled to superconductivity by the cold head (212), which exerts a repetitive motion, the method comprising the steps of measuring a periodic occurrence of spatial field components of the B-field based on a motion of the cold head (212) as a function of time, performing a sensor measurement of a periodic, auxiliary parameter of the MR imaging system (110), which is not the periodic occurrence of spatial field components, synchronizing the periodic occurrence of spatial field components of the B-field with the measured periodic, auxiliary parameter of the MR imaging system (110), and triggering based on the measured periodic sensor measurement of the MR imaging system (110) a periodic application of compensation signals to compensate the periodic occurrence of spatial field components of the B-field based on a motion of the cold head (212). Furthermore, the present invention provides a MR imaging system (110) for providing an image representation of a region of interest (142) of a subject of interest (120) positioned in an examination space (116) of the MR imaging system (110), wherein the MR imaging system (110) is adapted to perform the above method.

A shimming method and device, an electronic device, and a storage medium are disclosed. The shimming method includes: obtaining object static magnetic field distribution information corresponding to a target object, the object static magnetic field distribution information including the static magnetic field distribution information of the target object under the action of a main magnet of a magnetic resonance system; determining a target static magnetic field based on the object static magnetic field distribution information and a preset shim coil magnetic field distribution model; and adjusting at least one shim coil parameter in the shim coil magnetic field distribution model until a magnetic field uniformity of the target static magnetic field satisfies a preset condition, and accordingly obtaining at least one target shim coil parameter.

A shimming method and device, an electronic device, and a storage medium are disclosed. The shimming method includes: obtaining object static magnetic field distribution information corresponding to a target object, the object static magnetic field distribution information including the static magnetic field distribution information of the target object under the action of a main magnet of a magnetic resonance system; determining a target static magnetic field based on the object static magnetic field distribution information and a preset shim coil magnetic field distribution model; and adjusting at least one shim coil parameter in the shim coil magnetic field distribution model until a magnetic field uniformity of the target static magnetic field satisfies a preset condition, and accordingly obtaining at least one target shim coil parameter.