Abstract: 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.

Abstract: The present disclosure relates to a system and method for MRI with respect to vessels and bleedings. The method may include exciting a region of interest by applying an RF pulse, wherein the region of interest includes a vessel region and a bleeding region. The method may further include acquiring a plurality of echo signals related to the region of interest. The method may further include generating one or more magnitude images based on the plurality of echo signals, generating a first image with respect to the vessel region based on the one or more magnitude images, generating one or more phase images based on the plurality of echo signals, and generating a second image with respect to a distribution of susceptibility of the bleeding region based on the one or more phase images.

Abstract: A system is provided in the present disclosure. The system may acquire a first set of echo signals and a second set of echo signals relating to a subject. The first and the second set may be generated by using an MR scanner to execute a first acquisition and a second acquisition on the subject, respectively. The first acquisition may include at least a first repetition and a second repetition with different repetition times. Each of the first and second repetitions may have a first flip angle. The second acquisition may include at least a third repetition and a fourth repetition with different repetition times. Each of the third repetition and the fourth repetition may have a second flip angle different from the first flip angle. The system may also perform a measurement on the subject based on at least one of the first set or the second set.

Abstract: A method for determining a signal representation of a subject in MRI is provided. The method may include acquiring a plurality of signals of the subject. The plurality of signals may be generated using an MRI device, and each of the plurality of signals may correspond to a set of values in a plurality of signal dimensions of signal acquisition using the MRI device. The method may include determining, among the plurality of signal dimensions, a primary signal dimension and at least one secondary signal dimension, the primary signal dimension being associated with the signal representation. The method may also include determining the signal representation of the subject based on the primary signal dimension, the at least one secondary signal dimension, and the plurality of signals.

Abstract: An MRI system is provided. The system may obtain a first set of MRI data relating to a subject acquired by an MR scanner in a first acquisition when the subject reaches a first T1 weighting level, and obtain a second set of MRI data relating to the subject acquired by the MR scanner in a second acquisition when the subject reaches a second T1 weighting level different from the first T1 weighting level. The system may also determine a target value of a reference coefficient associated with a first B1 inhomogeneity in the first acquisition and a second B1 inhomogeneity in the second acquisition based on the first and second sets of MRI data.

Abstract: The present disclosure is related to systems and methods for determining a field map in magnetic resonance imaging (MRI). The method includes obtaining at least three images. Each may be acquired at one of at least three echo times by an MRI device via scanning a subject. The at least three echo times may define multiple pairs of adjacent echo times. Each of the multiple pairs of adjacent echo times may have a time difference between the adjacent echo times. At least two of the time differences may be different. The method includes determining a target function with an off-resonance frequency as an independent variable. The target function includes a phase deviation term and a sparsity constraint term.

Abstract: A method for determining a signal representation of a subject in MRI is provided. The method may include acquiring a plurality of signals of the subject. The plurality of signals may be generated using an MRI device, and each of the plurality of signals may correspond to a set of values in a plurality of signal dimensions of signal acquisition using the MRI device. The method may include determining, among the plurality of signal dimensions, a primary signal dimension and at least one secondary signal dimension, the primary signal dimension being associated with the signal representation. The method may also include determining the signal representation of the subject based on the primary signal dimension, the at least one secondary signal dimension, and the plurality of signals.

Abstract: The disclosure provides a system for noise analysis. The system may acquire a plurality of signals of a subject, and determine a signal representation of the subject based on the plurality of signals. The system may determine an updated signal representation of the subject by adding a signal disturbance into the plurality of signals. The system may further determine a value of a noise parameter indicative of a signal level of the plurality of signals relative to noise of the plurality of signals based on the signal representation and the updated signal representation of the subject.

Abstract: A method may include obtaining first image data of a first subject and obtaining a target machine learning model. The first image data may indicate a first intensity distribution of a first magnetic field relative to at least one portion of the first subject. The target machine learning model may provide a mapping relationship between second intensity distributions of second magnetic fields and corresponding second susceptibility distributions associated with second subjects under the second magnetic fields. The method may also include generating a first susceptibility distribution associated with the first subject under the first magnetic field based on the target machine learning model and the first image data. The method may further include determining a target MR image of the at least one portion of the first subject based on the first susceptibility distribution.

Abstract: The present disclosure relates to systems and methods for vehicle management. The systems may perform the methods to obtain a plurality of echo signals representing a subject, the plurality of echo signals being formed at a plurality of different echo times; generate a plurality of phase wrapped images based on the plurality of echo signals, each phase wrapped image comprising one or more first wrapped values; generate a phase difference map based on the plurality of phase wrapped images, the phase difference map comprising one or more second wrapped values; generate an unwrapped phase difference map by unwrapping the one or more second wrapped values in the phase difference map; determine a first field distribution map based on the unwrapped phase difference map; and generate a plurality of unwrapped phase images by unwrapping the one or more first wrapped values in each phase wrapped image based on the first field distribution map.

Abstract: A method may include obtaining first image data of a first subject and obtaining a target machine learning model. The first image data may indicate a first intensity distribution of a first magnetic field relative to at least one portion of the first subject. The target machine learning model may provide a mapping relationship between second intensity distributions of second magnetic fields and corresponding second susceptibility distributions associated with second subjects under the second magnetic fields. The method may also include generating a first susceptibility distribution associated with the first subject under the first magnetic field based on the target machine learning model and the first image data. The method may further include determining a target MR image of the at least one portion of the first subject based on the first susceptibility distribution.

Abstract: A method for determining a flow sensitive gradient block includes determine a gradient parameter for one or more echoes in an imaging sequence according to a scanning protocol. The method also includes determining one or more time origins for gradient moment calculation based on the gradient parameter and obtaining one or more target zeroth-order gradient moments and one or more target first-order gradient moments corresponding to the one or more time origins. The method further includes determining one or more parameters of the one or more flow sensitive gradient blocks with respect to the one or more target zeroth-order gradient moments and the one or more target first-order gradient moment and updating the gradient parameter according to the one or more parameters of the one or more flow sensitive gradient blocks.

Abstract: 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.

Abstract: A system and method for magnetic resonance imaging is provided. The method may include: determining a scanning parameter, wherein the scanning parameter includes one or more predetermined values; obtaining one or more MR signal sets based on the one or more predetermined values; generating one or more original images based on the one or more MR signal sets, wherein an original image corresponds to an MR signal set; determining one or more virtual values associated with the scanning parameter; and generating one or more virtual images based on the one or more virtual values and the one or more original images, wherein a virtual image corresponds to a virtual value.

Abstract: A system and method for magnetic resonance imaging is provided. The method includes acquiring a plurality of echo signals relating to a region of interest of a subject at a number of echo times; generating a plurality of phase images based on the plurality of echo signals; generating an unwrapped phase map by performing a phase unwrapping correction to the plurality of phase images; generating a virtual phase map based on the unwrapped phase map; determining a phase mask based on the virtual phase map; obtaining magnitude information of the plurality of echo signals; and generating a susceptibility weighted image based on the phase mask and the magnitude information.

Abstract: The present disclosure relates to a system and method for MRI with respect to vessels and bleedings. The method may include exciting a region of interest by applying an RF pulse, wherein the region of interest includes a vessel region and a bleeding region. The method may further include acquiring a plurality of echo signals related to the region of interest. The method may further include generating one or more magnitude images based on the plurality of echo signals, generating a first image with respect to the vessel region based on the one or more magnitude images, generating one or more phase images based on the plurality of echo signals, and generating a second image with respect to a distribution of susceptibility of the bleeding region based on the one or more phase images.

Abstract: A method for determining a flow sensitive gradient block includes determine a gradient parameter for one or more echoes in an imaging sequence according to a scanning protocol. The method also includes determining one or more time origins for gradient moment calculation based on the gradient parameter and obtaining one or more target zeroth-order gradient moments and one or more target first-order gradient moments corresponding to the one or more time origins. The method further includes determining one or more parameters of the one or more flow sensitive gradient blocks with respect to the one or more target zeroth-order gradient moments and the one or more target first-order gradient moment and updating the gradient parameter according to the one or more parameters of the one or more flow sensitive gradient blocks.

Abstract: A system and method for magnetic resonance imaging is provided. The method includes acquiring a plurality of echo signals relating to a region of interest of a subject at a number of echo times; generating a plurality of phase images based on the plurality of echo signals; generating an unwrapped phase map by performing a phase unwrapping correction to the plurality of phase images; generating a virtual phase map based on the unwrapped phase map; determining a phase mask based on the virtual phase map; obtaining magnitude information of the plurality of echo signals; and generating a susceptibility weighted image based on the phase mask and the magnitude information.

Abstract: The present disclosure relates to systems and methods for vehicle management. The systems may perform the methods to obtain a plurality of echo signals representing a subject, the plurality of echo signals being formed at a plurality of different echo times; generate a plurality of phase wrapped images based on the plurality of echo signals, each phase wrapped image comprising one or more first wrapped values; generate a phase difference map based on the plurality of phase wrapped images, the phase difference map comprising one or more second wrapped values; generate an unwrapped phase difference map by unwrapping the one or more second wrapped values in the phase difference map; determine a first field distribution map based on the unwrapped phase difference map; and generate a plurality of unwrapped phase images by unwrapping the one or more first wrapped values in each phase wrapped image based on the first field distribution map.

Abstract: A system and method for magnetic resonance imaging is provided. The method may include: determining a scanning parameter, wherein the scanning parameter includes one or more predetermined values; obtaining one or more MR signal sets based on the one or more predetermined values; generating one or more original images based on the one or more MR signal sets, wherein an original image corresponds to an MR signal set; determining one or more virtual values associated with the scanning parameter; and generating one or more virtual images based on the one or more virtual values and the one or more original images, wherein a virtual image corresponds to a virtual value.