The invention provides for a magnetic resonance imaging system (100, 300, 100) for acquiring magnetic resonance data (110, 1104) from a subject (118) within an imaging zone (108). The magnetic resonance imaging system comprises a memory (136) for storing machine executable instructions (160, 162, 164, 166, 316) and pulse sequence data (140, 1102). The pulse sequence data comprises instructions for controlling the magnetic resonance imaging system to acquire magnetic resonance data according to a magnetic resonance imaging method. The magnetic resonance imaging system further comprises a processor (130) for controlling the magnetic resonance imaging system. Execution of the machine executable instructions causes the processor to: acquire (1200) the magnetic resonance data by controlling the magnetic resonance imaging system with the pulse sequence data; calculate (1202) a B0 inhomogeneity map (148) by analyzing the magnetic resonance data according to the magnetic resonance imaging method, calculate (1204) a B1 phase map (150) and/or a B1 amplitude map (1106) by analyzing the magnetic resonance data according to the magnetic resonance imaging method; and calculate (1206) a second derivative (1110) of the B1 phase map and/or a second derivative of the B1 magnitude map 1 and/or a second derivative of the B0 in homogeneity map in at least one predetermined direction. The second derivative is calculated using a corrected voxel size in the at least one predetermined direction, wherein the corrected voxel size is calculated using a correction factor calculated from the derivative of the B0 inhomogeneity map.

An image processing apparatus according to an embodiment includes processing circuitry. The processing circuitry is configured to obtain two magnetic resonance images corresponding to two phase encoding directions opposite to each other. The processing circuitry is configured to generate a shift map related to shifting a plurality of pixels in the two magnetic resonance images, by optimizing a cost function using a first difference between the two magnetic resonance images and a second difference between two edge images generated on the basis of the two magnetic resonance images. The processing circuitry is configured to generate a correction image obtained by correcting distortions of the two magnetic resonance images on the basis of the two magnetic resonance images and the shift map.

A main magnetic field correction method for a magnetic resonance imaging system 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.

The disclosure provides a modified EPI sequence for acquiring multi-shot and multi-echo images with interleaved blip-up and blip-down phase encoding; the blip-up and blip-down images are processed by topup in FSL to estimate the inhomogeneous main magnetic field B.sub.0 map that causes image distortions; the B.sub.0 map is then incorporated into the encoding matrix with a low rank constraint to form a joint reconstruction model; the joint reconstruction model is solved to obtain multiple distortion-free images; and the multiple distortion-free images are matched to dictionary to simultaneous acquire the quantitative T.sub.2 (=1/R.sub.2) and T.sub.2* (=1/R.sub.2*) maps. In the phantom and in-vivo measurements, the disclosed method rapidly acquires the comparable quantitative images within one hold-breath (for 20 s) to the conventional mapping method, thus providing important practical application value for evaluation of liver damage, iron level and cancer lesion.

Systems and methods for designing and fabricating three-dimensional objects with precisely computed material compositions for use in enhancing electromagnetic fields for magnetic resonance imaging (“MRI”) are provided. As examples, the fabricated object can be designed to reduce magnetic field inhomogeneities in the main magnetic field of an MRI system, or to reduce inhomogeneities in a transmit radio frequency (“RF”) field (i.e., a B.sub.1 field). As examples, the object can be a shim; a housing or other part of an RF coil; a medical device, such as a surgical implant; or component used in a medical device, such as a housing for an implantable medical device.

A method for ascertaining a magnetic field of at least one magnetic coil unit of a magnetic resonance apparatus, a magnetic resonance apparatus, and a computer program product are provided. According to the method, the magnetic field is generated by the at least one magnetic coil unit. A plurality of magnetic field vectors are detected at different positions of the magnetic field by a magnetic field sensor unit, where each magnetic field vector of the plurality of magnetic field vectors describes a strength, such as a magnitude, and a direction of the magnetic field at the respective position. The magnetic field is ascertained. To ascertain the magnetic field based on the plurality of magnetic field vectors, a model of a vector field is ascertained.

A method for magnetic resonance imaging (MRI) may include obtaining a magnetic resonance (MR) image of a subject, wherein the MR image may be acquired based on a first MRI device and include at least one region of interest (ROI) of the subject. The method may also include selecting, based on the MR image and an ROI determination model, a portion of a main magnetic field generated by the first MRI device. The selected portion of the main magnetic field may correspond to the at least one ROI. The method may also include performing a magnetic field homogenization operation on the selected portion of the main magnetic field.

Systems and methods for determining a distribution map of susceptibility property of an object are provided. The method may include one or more of the following operations. A phase diagram corresponding to a magnetic resonance (MR) signal of the object may be obtained. A preliminary field map may be determined based on the phase diagram. Preliminary error limiting information associated with the preliminary field map may be obtained. A preliminary distribution map of susceptibility property of the object may be determined based on the preliminary field map and the preliminary error limiting information. An iteration process including at least one iteration may be performed to determine a target distribution map of susceptibility property of the object.

In a method for actuating a magnetic resonance system including a radio-frequency unit configured to generate a radio-frequency (RF) pulse for saturating nuclear spins in an examination area of an examination object, a BO card of the magnetic resonance system is loaded, frequency information of nuclear spins to be saturated in the examination area is loaded, a subarea of the examination area in which nuclear spins are to be saturated is determined, at least one RF saturation pulse for saturating the nuclear spins to be saturated in the determined subarea is determined based on the BO card and the frequency information, and the RF saturation pulse is output via the radio-frequency unit of the magnetic resonance system.

A method for actuating a magnetic resonance system having a radiofrequency unit designed to generate a radiofrequency pulse for the saturation of nuclear spins in an area under examination of an object under examination. The method includes loading a B0 map of the magnetic resonance system; loading frequency information on nuclear spins to be saturated in the area under examination; ascertaining at least one global RF saturation pulse for the global saturation of the nuclear spins to be saturated on the basis of the B0 map and the frequency information; and outputting the RF saturation pulse via the radiofrequency unit of the magnetic resonance system.