A method of manufacturing electromagnet coils for use in a magnetic resonance imaging (MRI) system is provided. The electromagnet coils are located in a non-homogeneous external magnetic field. The method comprises forming a coil representation of a coil surface for the electromagnet coils; setting limits for performance metrics for the electromagnet coils including a magnetic field-shape metric and at least one of an external torque metric and an external force metric, the external torque metric and the external force metric based, respectively, at least in part on a torque and a force exerted on the electromagnet coil by the non-homogeneous external magnetic field; forming a performance functional, based on the coil representation and the performance metrics, for generating a current density pattern over the coil surface; optimizing the performance functional and generating a current density pattern based on the optimized performance functional; and obtaining coil windings.

A method of manufacturing electromagnet coils for use in a magnetic resonance imaging (MRI) system is provided. The electromagnet coils are located in a non-homogeneous external magnetic field. The method comprises forming a coil representation of a coil surface for the electromagnet coils; setting limits for performance metrics for the electromagnet coils including a magnetic field-shape metric and at least one of an external torque metric and an external force metric, the external torque metric and the external force metric based, respectively, at least in part on a torque and a force exerted on the electromagnet coil by the non-homogeneous external magnetic field; forming a performance functional, based on the coil representation and the performance metrics, for generating a current density pattern over the coil surface; optimizing the performance functional and generating a current density pattern based on the optimized performance functional; and obtaining coil windings.

A method and apparatus for accessing and imaging at least one body part of interest may position a subject in an imaging system to partially encloses the subject and partially expose the subject, and access at least one body part of the subject that is exposed outside the imaging system for a procedure. The at least one exposed body part is positioned to be imaged by the imaging system.

A method for performing magnetic resonance imaging is provided. The method includes providing a magnetic resonance imaging system comprising: a radio frequency receive system comprising a radio frequency receive coil, and a housing, wherein the housing comprises a permanent magnet for providing an inhomogeneous permanent gradient field, a radio frequency transmit system, and a single-sided gradient coil set. The method also includes placing the receive coil proximate a target subject; applying a sequence of chirped pulses via the transmit system; applying a multi-slice excitation along the inhomogeneous permanent gradient field; applying a plurality of gradient pulses via the gradient coil set orthogonal to the inhomogeneous permanent gradient field; acquiring a signal of the target subject via the receive system, wherein the signal comprises at least two chirped pulses; and forming a magnetic resonance image of the target subject.

A method for performing magnetic resonance imaging is provided. The method includes providing a magnetic resonance imaging system comprising: a radio frequency receive system comprising a radio frequency receive coil, and a housing, wherein the housing comprises a permanent magnet for providing an inhomogeneous permanent gradient field, a radio frequency transmit system, and a single-sided gradient coil set. The method also includes placing the receive coil proximate a target subject; applying a sequence of chirped pulses via the transmit system; applying a multi-slice excitation along the inhomogeneous permanent gradient field; applying a plurality of gradient pulses via the gradient coil set orthogonal to the inhomogeneous permanent gradient field; acquiring a signal of the target subject via the receive system, wherein the signal comprises at least two chirped pulses; and forming a magnetic resonance image of the target subject.

Disclosed are a pulse magnet device based on magnetic flux compression, and a high-flux measurement method. The device includes a diamagnetic block, reinforcing plates, screw rods and a magnet coil. The diamagnetic block and the magnet coil are concentrically arranged in the axial direction; the reinforcing plates are arranged at ends of the magnet coil and the diamagnetic block and are connected by means of the screw rods. The diamagnetic block is used for inducing the induction current opposite the coil current during the discharge of the magnet coil, and for compressing the magnetic field to the area between the diamagnetic block and the magnet coil. The intensity and uniformity of the magnetic field around the magnet coil are improved by means of increasing the magnetic flux density.

Disclosed are a pulse magnet device based on magnetic flux compression, and a high-flux measurement method. The device includes a diamagnetic block, reinforcing plates, screw rods and a magnet coil. The diamagnetic block and the magnet coil are concentrically arranged in the axial direction; the reinforcing plates are arranged at ends of the magnet coil and the diamagnetic block and are connected by means of the screw rods. The diamagnetic block is used for inducing the induction current opposite the coil current during the discharge of the magnet coil, and for compressing the magnetic field to the area between the diamagnetic block and the magnet coil. The intensity and uniformity of the magnetic field around the magnet coil are improved by means of increasing the magnetic flux density.

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B.sub.0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B.sub.0 field.

In some aspects, a magnetic system for use in a low-field MRI system. The magnetic system comprises at least one electromagnet configured to, when operated, generate a magnetic field to contribute to a B.sub.0 field for the low-field MRI system, and at least one permanent magnet to produce a magnetic field to contribute to the B.sub.0 field.

According to some aspects, a method of producing a permanent magnet shim configured to improve a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The method comprises determining deviation of the B.sub.0 magnetic field from a desired B.sub.0 magnetic field, determining a magnetic pattern that, when applied to magnetic material, produces a corrective magnetic field that corrects for at least some of the determined deviation, and applying the magnetic pattern to the magnetic material to produce the permanent magnet shim. According to some aspects, a permanent magnet shim for improving a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The permanent magnet shim comprises magnetic material having a predetermined magnetic pattern applied thereto that produces a corrective magnetic field to improve the profile of the B.sub.0 magnetic field.