Abstract: A magnetic resonance imaging (MRI) system includes a set of magnet coils for generating a magnetic field. The set of magnet coils are composed of a superconducting material. The system further includes a mechanical cryocooler in thermal contact with the set of magnet coils and operable to reduce and maintain a temperature of the set of magnet coils below a transition temperature of the superconducting material, and an energy storage device coupled to the set of magnet coils. The energy storage device may be capable of receiving and storing energy dissipated from the set of magnet coils during rapid shutdown of the set of magnet coils. The system may also include a controller coupled to the energy storage device. The controller may be programmed to recharge the set of magnet coils using the energy stored in the energy storage device during the rapid shutdown of the set of magnet coils.

Abstract: A method is provided for magnetic resonance (MR) imaging near metal, including acquiring an image at a first magnetic field from a subject that includes a metal object, acquiring an image at a second magnetic field, and combining the images to provide a corrected image with reduced metal distortion. An MR imaging system for measuring near metal is also provided including a superconducting magnet to provide a magnetic field, a power supply for a current to ramp the magnetic field, a cryocooler in contact with the superconducting magnet, a magnetic field controller programmed to ramp the main magnetic field by adjusting the current generated by the power supply, a radio frequency system for transmitting and receiving signals, and a data acquisition and processing system to receive the MR signals, generate image data sets and combine the image data sets to provide a corrected image having a reduced metal distortion.

Abstract: Methods for correcting a non-uniform power response of a radiofrequency (“RF”) transmit coil used in magnetic resonance imaging (“MRI”) are described. Transmit power response data for an RF transmit coil are processed to compute RF amplitude scaling factors for the RF transmit coil as a function of transmit frequency offset. The RF amplitude scaling factors can be used to correct transmitted RF power, and thus flip angle, to be more uniform over a range of transmit frequency offsets, as may be encountered when imaging with lower field MRI systems or MRI systems with high strength or asymmetric gradients.

Abstract: 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.

Abstract: Some implementations provide a system that includes: a housing having a bore in which a subject to be image 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; one or more gradient coils configured to linearly vary the volume of magnetic field as a function of spatial location; one or more 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; one or more 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.

Abstract: The present disclosure reports on a method to first determine the required electromagnetic stream function, and then iterate on the contouring of the stream function to optimize the force, torque, shielding, and/or mutual inductance of the design after-the-fact without compromising the electromagnetic performance and an electromagnetic coil manufacture according to the method. These parameters are sensitive to the precise positioning of the discrete wires.

Abstract: An asymmetric electromagnet system, method, and method of producing an asymmetric electromagnet system, wherein the asymmetric electromagnet system is for generating an imaging magnetic field in an imaging region with an imaging isocentre, the imaging region being asymmetrically positioned within a gradient coil bore inside a magnetic resonance imaging (MRI) system during imaging, the electromagnet assembly comprising: an asymmetric gradient coil configured to generate a gradient field in the asymmetrically positioned imaging region, at least one gradient axis having the gradient field with a constant offset component such that the position at which the gradient field passes through zero is offset with respect to the imaging isocentre of the asymmetrically positioned imaging region.

Abstract: A coil apparatus and methods for magnetic resonance imaging involving a wire winding, the wire winding having at least one of: a hollow cross-section wire and a solid cross-section wire, the solid cross-section wire having at least one of: a solid small cross-section wire and a solid large cross-section wire, the solid large cross-section wire having a thickness greater than that of the solid small cross-section wire, and the solid small cross-section wire disposed in one of adjacent and proximate at least one of the hollow cross-section wire and the solid large cross-section wire, whereby at least one of current density, winding density, and heat extraction are increasable.

Abstract: Some implementations provide a system that includes: a housing having a bore in which a subject to be image 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; one or more gradient coils configured to linearly vary the volume of magnetic field as a function of spatial location; one or more 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; one or more 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.

Abstract: An automatic protocolling system and methods involving a processor operable by way of a set of executable instructions storable in relation to a nontransient memory device, the set of executable instructions configuring the processor to: receive information relating to an initial protocol comprising an initial ordering of a plurality of sequences, the information comprising data relating to an interaction extent value of at least one of an imaging system and a patient as a function of time corresponding to each sequence in the plurality of sequences, the data relating to a time-integrated effect of each sequence in the plurality of sequences; and dynamically determine an alternative protocol comprising an alternative ordering of the plurality of sequences based on the time-integrated effect, whereby an alternative protocol is provided.

Abstract: A coil apparatus and methods for magnetic resonance imaging involving a wire winding, the wire winding having at least one of: a hollow cross-section wire and a solid cross-section wire, the solid cross-section wire having at least one of: a solid small cross-section wire and a solid large cross-section wire, the solid large cross-section wire having a thickness greater than that of the solid small cross-section wire, and the solid small cross-section wire disposed in one of adjacent and proximate at least one of the hollow cross-section wire and the solid large cross-section wire, whereby at least one of current density, winding density, and heat extraction are increasable.

Abstract: An asymmetric electromagnet system, method, and method of producing an asymmetric electromagnet system, wherein the asymmetric electromagnet system is for generating an imaging magnetic field in an imaging region with an imaging isocentre, the imaging region being asymmetrically positioned within a gradient coil bore inside a magnetic resonance imaging (MRI) system during imaging, the electromagnet assembly comprising: an asymmetric gradient coil configured to generate a gradient field in the asymmetrically positioned imaging region, at least one gradient axis having the gradient field with a constant offset component such that the position at which the gradient field passes through zero is offset with respect to the imaging isocentre of the asymmetrically positioned imaging region.

Abstract: An asymmetric electromagnet system, method, and method of producing an asymmetric electromagnet system, wherein the asymmetric electromagnet system is for generating an imaging magnetic field in an imaging region with an imaging isocentre, the imaging region being asymmetrically positioned within a gradient coil bore inside a magnetic resonance imaging (MRI) system during imaging, the electromagnet assembly comprising: an asymmetric gradient coil configured to generate a gradient field in the asymmetrically positioned imaging region, at least one gradient axis having the gradient field with a constant offset component such that the position at which the gradient field passes through zero is offset with respect to the imaging isocentre of the asymmetrically positioned imaging region.

Abstract: A method for operating a magnetic resonance imaging (MRI) system that includes: accessing data indicating a first region for imaging a portion of a subject, the portion being placed in a main magnet of the MRI system and the main magnet generating a magnetic field; selecting, from a group of available shimming coils, a first subset of shimming coils arranged and configured such that, when the shimming coils in the first subset are driven, a homogeneity of the magnetic field at the first region is increased; and driving the shimming coils in the selected first subset of shimming coils without driving other shimming coils in the group of available shimming coils such that the homogeneity of the magnetic field at the first region increases relative to the homogeneity of the magnetic field at the first region when the shimming coils of the selected first subset are not driven.

Abstract: A fat saturation method for a magnetic resonance imaging system having a main magnet providing a magnetic field B0 The method includes: driving a shim coil assembly with a first set of shimming currents to sufficiently alter a B0 field inhomogeneity of the magnetic field B0 within a region that includes a first imaging volume of interest such that water saturation inside the region is reduced from before the first set of shimming currents are applied; applying a fat saturation pulse to the region; identifying the first imaging volume of interest from the region; driving the shim coil assembly with a second set of shimming currents to alter the B0 field inhomogeneity of the magnetic field B0 within the first imaging volume of interest such that the B0 field inhomogeneity within the first imaging volume of interest is reduced; and obtaining magnetic resonance signals from the first imaging volume of interest.

Abstract: Some implementations provide an MRI system that includes: a housing having a bore accommodating a portion of a subject; a main magnet enclosed by said housing and configured to generate a substantially uniform magnet field within the bore; a gradient sub-system to provide perturbations to the substantially uniform magnet field; a flexible coil assembly configured to (i) receive radio frequency (RF) signals from the subject in response to the portion of the subject being scanned, and (ii) generate and apply B0 shimming to improve a field homogeneity of the substantially uniform magnetic field; and a control unit configured to: drive the gradient sub-system using a gradient waveform; and receive measurement results responsive to the gradient waveform such that a coupling between the gradient sub-system and the flexible coil assembly is determined and subsequently reduced in response to the determined coupling exceeding a pre-determined threshold.

Abstract: Systems and methods for magnetic field-dependent relaxometry using magnetic resonance imaging (“MRI”) are provided. Relaxation parameters, including longitudinal relaxation time (“T1”) and transverse relaxation time (“T2”), are estimated from magnetic resonance signal data acquired at multiple different magnetic field strengths using the same MRI system. By measuring these relaxation parameters as a function of magnetic field strength, T1 dispersion data, T2 dispersion data, or both, are generated. Based on this dispersion data, quantitative physiological parameters can be estimated. As one example, iron content can be estimated from T2 dispersion data.

Abstract: The present disclosure reports on a method to first determine the required electromagnetic stream function, and then iterate on the contouring of the stream function to optimize the force, torque, shielding, and/or mutual inductance of the design after-the-fact without compromising the electromagnetic performance and an electromagnetic coil manufacture according to the method. These parameters are sensitive to the precise positioning of the discrete wires.

Abstract: A fat saturation method for a magnetic resonance imaging system having a main magnet providing a magnetic field B0 The method includes: driving a shim coil assembly with a first set of shimming currents to sufficiently alter a B0 field inhomogeneity of the magnetic field B0 within a region that includes a first imaging volume of interest such that water saturation inside the region is reduced from before the first set of shimming currents are applied; applying a fat saturation pulse to the region; identifying the first imaging volume of interest from the region; driving the shim coil assembly with a second set of shimming currents to alter the B0 field inhomogeneity of the magnetic field B0 within the first imaging volume of interest such that the B0 field inhomogeneity within the first imaging volume of interest is reduced; and obtaining magnetic resonance signals from the first imaging volume of interest.

Abstract: A fat saturation method for a magnetic resonance imaging system having a main magnet providing a magnetic field B0 The method includes: driving a shim coil assembly with a first set of shimming currents to sufficiently alter a B0 field inhomogeneity of the magnetic field B0 within a region that includes a first imaging volume of interest such that water saturation inside the region is reduced from before the first set of shimming currents are applied; applying a fat saturation pulse to the region; identifying the first imaging volume of interest from the region; driving the shim coil assembly with a second set of shimming currents to alter the B0 field inhomogeneity of the magnetic field B0 within the first imaging volume of interest such that the B0 field inhomogeneity within the first imaging volume of interest is reduced; and obtaining magnetic resonance signals from the first imaging volume of interest.