The disclosure relates to a method for generating a B.sub.0 map for a magnetic resonance examination of an examination subject, a magnetic resonance device, and a computer program product for executing the method. The method provides for the application of at least two preparatory RF pulses during a preparatory stage and at least one readout RF pulse during an acquisition stage. At least one stimulated echo signal is acquired after the readout RF pulse. A B.sub.0 map that shows the actual spatial distribution of the magnetic field strength of the main magnetic field is derived from the at least one acquired FID echo signal and the at least one acquired stimulated echo signal.

The present disclosure provides a system for MRI. The system may obtain a plurality of echo signals relating to a subject that are excited by an MRI pulse sequence applied to the subject. The system may perform a quantitative measurement on the subject based on the plurality of echo signals. The MRI pulse sequence may include a CEST module configured to selectively excite exchangeable protons or exchangeable molecules in the subject, an RF excitation pulse applied after the CEST module configured to excite a plurality of gradient echoes, and one or more refocusing pulses applied after the RF excitation pulse. Each of the refocusing pulses may be configured to excite one or more spin echoes. The one or more spin echoes excited by at least one of the one or more refocusing pulses may include a symmetric spin echo and one or more asymmetric spin echoes.

Retrospective magnetic resonance imaging (MRI) uses a deep neural network framework [102] to generate from MRI imaging data [100] acquired by an MRI apparatus using a predetermined imaging protocol tissue relaxation parametric maps and magnetic/radiofrequency field maps [104] which are then used to generate using the Bloch equations [106] predicted MRI images [108] corresponding to imaging protocols distinct from the predetermined imaging protocol. This allows obtaining a wide spectrum of tissue contrasts distinct from those of the acquired MRI imaging data.

A method for performing a magnetic resonance measurement of a patient using a magnetic resonance apparatus is provided. The magnetic resonance apparatus includes a radiofrequency antenna unit for producing an excitation pulse. A first B0 field map for a first motion state of the patient, and a second B0 field map for a second motion state of the patient are provided. A first excitation pulse for the first motion state, and a second excitation pulse for the second motion state are determined based on the first B0 field map and the second B0 field map. A magnetic resonance measurement is performed, during which the motion state of the patient is monitored. When the patient is in the first motion state, the radiofrequency antenna unit transmits the first excitation pulse. When the patient is in the second motion state, the radiofrequency antenna unit transmits the second excitation pulse.

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.

A method of analysing the magnitude of Magnetic Resonance Imaging (MRI) data is described. The method comprising: using the magnitude only of the multi-echo MRI data of images from the subject, where images are acquired at arbitrarily timed echoes including at least one echo time where water and fat are not substantially in-phase; fitting the magnitude of said multi-echo MRI data to a single signal model to produce a plurality of potential solutions for the relative signal contributions for each of the at least two species from the model, by using a plurality of different starting conditions to generate a particular cost function value for each of the plurality of starting conditions, where said cost function values are independent of a field map term for the MRI data; analysing said cost function values to calculate relative signal separation contribution for each species at each voxel of the images.

A shimming system for magnetic resonance imaging is provided, which includes: a multi-channel local shim coil unit configured to be installed on an inspection table of a magnetic resonance imaging system, where the multi-channel local shim coil unit includes a local multi-channel shim coil and a radio frequency receiving coil for receiving magnetic resonance signals, and the radio frequency receiving coil is placed inside the local multi-channel shim coil and separated by a distance from the local multi-channel shim coil; a computer control system configured to install and set software controlled by a DC power and calculate field maps and calculate optimization processes; a DC power system communicatively connected to the computer control system to control a value of current of each channel; and a housing having a semi-cylindrical configuration, where the local multi-channel shim coil is only distributed on a semi-cylindrical surface of the semi-cylindrical configuration of the housing.

A MRI device including a main field unit for establishing a main magnetic field (MF) in an imaging region, a gradient coil assembly for generating a gradient field in the imaging region, a RF arrangement for sending excitation signals to and receiving MR signals from the imaging region, a field camera for determining MF information in the imaging region, the field camera comprising multiple MF sensors arranged at measurement positions enclosing the imaging region, and a controller. The controller is configured to receive sensor data for each measurement positions, from the sensor data, calculate the MF information for the imaging region, and implement a calibration and/or correction measure depending on the MF information. The field camera may be a vector-field camera acquiring vector-valued sensor data describing the MF at each measurement positions three-dimensionally. The controller may determine the MF information to three dimensionally describe the MF in the imaging region.

In a method for control, input magnetic field map data is received. In this case, the input magnetic field map data for at least one magnetic field type in each case describes a magnetic field map for a state that an examination object is in at an initial location in the MR apparatus. In this case, the estimated magnetic field map data for at least one magnetic field type in each case describes at least one magnetic field map for in each case a state that the examination object is in at an alternative location that is different compared to the initial location. Control data is determined by the system control unit, using the estimated magnetic field map data or using the input magnetic field map data and the estimated magnetic field map data. The control data is suitable for controlling the MR apparatus.

Provided in embodiments of the present invention are a magnetic resonance imaging system and a main magnetic field correction method therefor, and a storage medium. Specifically, provided are a magnetic resonance imaging system, a main magnetic field correction method for the magnetic resonance imaging system, and a computer-readable storage medium. The method includes: obtaining an estimated image of a phantom based on a first imaging sequence, the first imaging sequence having a variable resonant frequency; pre-correcting a main magnetic field based on the estimated image; obtaining a scanned image of the phantom based on the pre-corrected main magnetic field; and determining whether the quality of the scanned image is within an acceptable range, and if not, returning to the step of obtaining the estimated image.