A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

A pre-polarisation magnet arrangement for generating a pre-polarisation field for use in a low field magnetic resonance imaging process, the pre-polarisation magnet arrangement including a pre-polarisation field array including a plurality of permanent pre-polarisation magnets mounted in a support and provided in a circumferentially spaced arrangement surrounding an field of view, a number of the pre-polarisation magnets being movable between respective first and second positions, wherein in the first position the pre-polarisation magnets are configured as a cylindrical Halbach array to generate a pre-polarisation field in the field of view and in the second position the pre-polarisation magnets are configured to minimize the pre-polarisation field in the field of view.

A pre-polarisation magnet arrangement for generating a pre-polarisation field for use in a low field magnetic resonance imaging process, the pre-polarisation magnet arrangement including a pre-polarisation field array including a plurality of permanent pre-polarisation magnets mounted in a support and provided in a circumferentially spaced arrangement surrounding an field of view, a number of the pre-polarisation magnets being movable between respective first and second positions, wherein in the first position the pre-polarisation magnets are configured as a cylindrical Halbach array to generate a pre-polarisation field in the field of view and in the second position the pre-polarisation magnets are configured to minimize the pre-polarisation field in the field of view.

Methods and apparatus for operating a low-field magnetic resonance imaging (MRI) system to perform diffusion weighted imaging, the low-field MRI system including a plurality of magnetics components including a B.sub.0 magnet configured to produce a low-field main magnetic field B.sub.0, at least one gradient coil configured to, when operated, provide spatial encoding of emitted magnetic resonance signals, and at least one radio frequency (RF) component configured to acquire, when operated, the emitted magnetic resonance signals. The method comprises controlling one or more of the plurality of magnetics components in accordance with at least one pulse sequence having a diffusion-weighted gradient encoding period followed by multiple echo periods during which magnetic resonance signals are produced and detected, wherein at least two of the multiple echo periods correspond to respective encoded echoes having an opposite gradient polarity.

Methods and apparatus for operating a low-field magnetic resonance imaging (MRI) system to perform diffusion weighted imaging, the low-field MRI system including a plurality of magnetics components including a B.sub.0 magnet configured to produce a low-field main magnetic field B.sub.0, at least one gradient coil configured to, when operated, provide spatial encoding of emitted magnetic resonance signals, and at least one radio frequency (RF) component configured to acquire, when operated, the emitted magnetic resonance signals. The method comprises controlling one or more of the plurality of magnetics components in accordance with at least one pulse sequence having a diffusion-weighted gradient encoding period followed by multiple echo periods during which magnetic resonance signals are produced and detected, wherein at least two of the multiple echo periods correspond to respective encoded echoes having an opposite gradient polarity.

A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

A superconductor magnet system (2) includes a cryostat (4), a superconductor bulk magnet (5), and a cryogenic cooling system (12). The bulk magnet (5) has at least N axially stacked bulk sub-magnets (6a-6c), with N≥3. Between each two axially neighboring bulk sub-magnets, an intermediate body (7a-7b) is arranged. The intermediate bodies (7a-7b) are made from a non-metallic thermal insulator material. The cryogenic cooling system (12) is adapted for independently controlling the temperature of each bulk sub-magnet (6a-6c), and has, for each bulk sub-magnet, a temperature sensor (16a-16c) for sensing the temperature of the respective bulk sub-magnet and an adjustment unit (13a-13c) for adjusting a heating power and/or a cooling power at the respective bulk sub-magnet.

An arrangement that enables performing of both magnetic particle imaging and magnetic resonance imaging and a device including the arrangement are provided. The arrangement that enables performance of both magnetic particle imaging and magnetic resonance imaging includes: at least one primary magnetic element pair configured to generate a selection magnetic field (SMF1/SMF2) for magnetic particle imaging, at least one secondary magnetic element pair configured to generate a driving magnetic field, and at least one tertiary magnetic element pair configured to generate a focus magnetic field (FMF).

An arrangement that enables performing of both magnetic particle imaging and magnetic resonance imaging and a device including the arrangement are provided. The arrangement that enables performance of both magnetic particle imaging and magnetic resonance imaging includes: at least one primary magnetic element pair configured to generate a selection magnetic field (SMF1/SMF2) for magnetic particle imaging, at least one secondary magnetic element pair configured to generate a driving magnetic field, and at least one tertiary magnetic element pair configured to generate a focus magnetic field (FMF).

According to some aspects, a portable magnetic resonance imaging system is provided, comprising a Bo magnet configured to produce a Bo magnetic field for an imaging region of the magnetic resonance imaging system, a noise reduction system configured to detect and suppress at least some electromagnetic noise in an operating environment of the portable magnetic resonance imaging system, and electromagnetic shielding provided to attenuate at least some of the electromagnetic noise in the operating environment of the portable magnetic resonance imaging system, the electromagnetic shielding arranged to shield a fraction of the imaging region of the portable magnetic resonance imaging system. According to some aspects, the electromagnetic shield comprises at least one electromagnetic shield structure adjustably coupled to the housing to provide electromagnetic shielding for the imaging region in an amount that can be varied. According to some aspects, substantially no shielding of the imaging region is provided.