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.

Methods and apparatuses for homogenizing or correcting the magnetic fields of magnets, particularly the magnetic fields employed in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) applications. There are disclosed passive shims for making such homogenizations or corrections, methods for making such shims, and a method and apparatus for creating desirable correction fields in which the correction field strength has limited harmonic content, near continuous value of field strength, and occupies minimal space in the magnet.

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.

Disclosed embodiments provide an apparatus and method for imaging breast tissue of a subject, wherein a subject is positioned on a structure so that at least a portion of the subject's body is supported by the structure, magnetic resonance imaging is performed on the portion of the subject's body using an MRI system including a plurality of MRI coils positioned in proximity to the structure, wherein, while the portion of the subject's body is positioned upon the structure, breast tissue of the subject's body is compressed in the proximity of plurality of MRI coils.

A magnetic resonance imaging device may include a field generator for generating at least one magnetic gradient field. The field generator may include a first magnet and a second magnet confining an imaging volume of the magnetic resonance imaging device in two spatial directions. The first magnet and the second magnet may be arranged asymmetrically with respect to the imaging volume. The magnetic resonance imaging device may be used to perform a method for acquiring an image of a diagnostically relevant body region of a patient.

A magnetic resonance imaging (MRI) system for infants and children and imaging method thereof are disclosed. The system includes: a base; a housing, with a bottom fixed to the base; a monitoring shield, pivotably connected to the top of the housing; a pair of open magnets, which are spaced apart from each other and fixed to the base by a magnet holder such that an imaging area is defined between them; an operating table, fixed in the imaging area; an incubator, movably connected to the operating table and configured to house an infant or child and to adjust the position of the infant or child in the imaging area. The monitoring shield has a closed configuration and an open configuration. In the closed configuration of the monitoring shield, the magnet holder, the open magnet, the operating table and the incubator are all situated within a space delimited by the base, the housing and the monitoring shield. With this optimized structure, the system allows a radiologist to more accurately and intuitively adjust and understand the position and angle at which the infant or child is imaged. In addition, with the incubator, the system can provide the infant or child with a safer and more comfortable environment. Therefore, it entails a systematic MRI solution for newborns, infants and children.

A cryocooler includes a second-stage cooling stage, a second cylinder which includes the second-stage cooling stage on a terminal of the second-stage cylinder, a second-stage displacer which includes a magnetic regenerator material and is accommodated in the second-stage cylinder so as to be able to reciprocate in the second-stage cylinder, and a tubular magnetic shield which is installed on the second-stage cooling stage and extends along the second-stage cylinder outside the second-stage cylinder. The magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is 60 MS (Mega-Siemens) to 1980 MS.

A radiation therapy system comprises a magnetic resonance imaging (MRI) system combined with an irradiation system, which can include one or more linear accelerators (linacs) that can emit respective radiation beams suitable for radiation therapy. The MRI system includes a split magnet system, comprising first and second main magnets separated by gap. A gantry is positioned in the gap between the main MRI magnets and supports the linac(s) of the irradiation system. The gantry is rotatable independently of the MRI system and can angularly reposition the linac(s). Shielding can also be provided in the form of magnetic and/or RF shielding. Magnetic shielding can be provided for shielding the linac(s) from the magnetic field generated by the MRI magnets. RF shielding can be provided for shielding the MRI system from RF radiation from the linac.

A Magnetic Resonance Imaging (MRI) system, including: two separate static magnetic field generators, which are each cylindrical, are axially aligned, and are separated by a rotary load-bearing structure arranged to freely rotate about an axis of a static magnetic field generated by the static magnetic field generators, wherein the rotary load-bearing structure is mounted on thrust bearings which take an axial load between the static magnetic field generators.

A gradient system for a magnetic resonance imaging system can include at least two examination areas using a common basic magnetic field and a number of gradient coils in the at least two examination areas, and a gradient controller configured such that it controls the electric current flowing through at least two gradient coils for similar gradient axes in different examination areas in a temporal synchronous manner.