Described here are systems and methods for mitigating or otherwise removing the effects of short-term magnetic field instabilities caused by oscillations of the cold head in a cryogen-free magnet system used for magnetic resonance systems, such as magnetic resonance imaging (“MRI”) systems, nuclear magnetic resonance (“NMR”) systems, or the like.

A superconductor bulk magnet magnetizing method providing a more homogenous trapped magnetic field includes: placing the bulk magnet inside a charger bore of an electrical charger magnet; placing a field correction unit inside a superconductor bore of the bulk magnet; applying an electrical current (I.sub.0) to the charger magnet, to generate an externally applied magnetic field, wherein a temperature T.sub.bulk of the bulk magnet exceeds a bulk magnet critical temperature T.sub.c; applying an auxiliary electrical current (I.sub.1, . . . ) to the field correction unit, thus generating an auxiliary magnetic field applied to the bulk magnet from within the superconductor bore, wherein T.sub.bulk>T.sub.c; lowering T.sub.bulk below T.sub.c; turning off the electrical current at the charger magnet, wherein T.sub.bulk<T.sub.c, and turning off the auxiliary electrical current at the field correction unit, wherein T.sub.bulk<T.sub.c; and removing the bulk magnet from the charger bore while T.sub.bulk<T.sub.c.

A superconductor bulk magnet magnetizing method providing a more homogenous trapped magnetic field includes: placing the bulk magnet inside a charger bore of an electrical charger magnet; placing a field correction unit inside a superconductor bore of the bulk magnet; applying an electrical current (I.sub.0) to the charger magnet, to generate an externally applied magnetic field, wherein a temperature T.sub.bulk of the bulk magnet exceeds a bulk magnet critical temperature T.sub.c; applying an auxiliary electrical current (I.sub.1, . . . ) to the field correction unit, thus generating an auxiliary magnetic field applied to the bulk magnet from within the superconductor bore, wherein T.sub.bulk>T.sub.c; lowering T.sub.bulk below T.sub.c; turning off the electrical current at the charger magnet, wherein T.sub.bulk<T.sub.c, and turning off the auxiliary electrical current at the field correction unit, wherein T.sub.bulk<T.sub.c; and removing the bulk magnet from the charger bore while T.sub.bulk<T.sub.c.

An electronic device (10) includes an electronic component (14); at least one electrically conductive loop or winding (18) disposed around the electronic component; and an electronic controller (24) configured to: obtain (102) a magnetic field direction from a received ambient magnetic field measurement signal; determine (104) at least one magnetic field shim current based on the obtained magnetic field direction; and energize (106) the at least one electrically conductive loop or winding to flow the determined at least one magnetic field shim current.

An electronic device (10) includes an electronic component (14); at least one electrically conductive loop or winding (18) disposed around the electronic component; and an electronic controller (24) configured to: obtain (102) a magnetic field direction from a received ambient magnetic field measurement signal; determine (104) at least one magnetic field shim current based on the obtained magnetic field direction; and energize (106) the at least one electrically conductive loop or winding to flow the determined at least one magnetic field shim current.

The invention relates to an MRI apparatus and a method of MRI involving the acquisition of a first and a second MRI image with mutually different orientations between the BO magnetic field and the object to be investigated. For instance, when imaging structures such as a tendon, due to the magic angle effect, this results in a change in image contrast. According to the invention, a coregistration can be performed between the first and the second MRI image. Moreover, the orientation of a structure within the object can be determined on the basis of the different orientations and the image intensity in the first and the second MRI image. The invention further discloses an apparatus for carrying out the method and a method of shimming the BO magnetic field of the apparatus.

The invention relates to an MRI apparatus and a method of MRI involving the acquisition of a first and a second MRI image with mutually different orientations between the BO magnetic field and the object to be investigated. For instance, when imaging structures such as a tendon, due to the magic angle effect, this results in a change in image contrast. According to the invention, a coregistration can be performed between the first and the second MRI image. Moreover, the orientation of a structure within the object can be determined on the basis of the different orientations and the image intensity in the first and the second MRI image. The invention further discloses an apparatus for carrying out the method and a method of shimming the BO magnetic field of the apparatus.

An NMR measuring arrangement (20) includes a cryostat (1), a superconducting magnet coil system (2) and an NMR probe (3). The cryostat has an evacuated vacuum container (5) and forms a bore (10). A wall (12) of the bore delimits the vacuum container. The cryostat forms only one evacuated gap (13) in a space (18) between the magnet coil system and the wall of the bore. At least a segment of the wall of the bore is thermally coupled to a heat sink of the cryostat. As a result, the NMR measurement arrangement provides more precise NMR measurements (in particular with a higher spectral resolution and/or a higher signal-to-noise ratio) on measurement samples.

A method for magnetic resonance imaging (MRI) may include obtaining a magnetic resonance (MR) image of a subject, wherein the MR image may be acquired based on a first MRI device and include at least one region of interest (ROI) of the subject. The method may also include selecting, based on the MR image and an ROI determination model, a portion of a main magnetic field generated by the first MRI device. The selected portion of the main magnetic field may correspond to the at least one ROI. The method may also include performing a magnetic field homogenization operation on the selected portion of the main magnetic field.

Magnetic resonance imaging (MRI) systems and methods, involving: a main magnet configured to generate a magnet field for MRI; a transmit radio frequency (RF) coil assembly configured to transmit an RF pulse into a portion of a subject; an RF coil assembly configured to, in response to the an RF pulse, receive MR signals emitted from the portion of the subject; and a gradient coil assembly having coil windings arranged in a radial layer and a first set of electrical connectors embedded in the radial layer to reduce a radial extent occupied by the gradient coil assembly, an electrical connector in the first set of electrical connectors configured to cross over a portion of the coil windings in the radial layer, the first set of electrical connectors configured to drive the coil windings with a current sufficient to generate a perturbation in the magnet field such that the MR signals encode an MR image based on the perturbation, and the radial layer having a depressed area configured to radially constrain the electrical connector.