A magnetic resonance (MR) imaging method of correcting phase errors is provided. The method includes applying, by an MR system, a pulse sequence to acquire the precorrection MR image. The method also includes acquiring, by the MR system, reference k-space data having a field of view (FOV) in a phase-encoding direction that is twice or more greater than an FOV of the precorrection MR image in the phase-encoding direction, wherein the reference k-space data and MR signals of the precorrection MR image are acquired with the same type of pulse sequences. The method further includes splitting the reference k-space data into first k-space data and second k-space data, generating a phase error map based on the first k-space data and the second k-space data, generating a phase-corrected image of the precorrection MR image based on the phase error map, and outputting the phase-corrected image.

To provide a technique in which, in imaging using an EPI method, an occurrence of an artifact when phase correction is performed for each channel is avoided and the phase correction is accurately performed. A common phase correction value to be applied to data of all channels is calculated using pre-scan data of each channel. The common phase correction value is obtained by combining a difference phase obtained for each of the channels. The difference phase is obtained by complex integration, while an absolute value of each channel is maintained as it is. The combination is performed by complex average, and averaging processing according to a weight of the absolute value is performed. The occurrence of an artifact can be prevented by using the common phase correction value, and robust phase correction can be performed by including the weight of the absolute value.

In a method for acquiring measurement data of an object, a first subsampled set of diffusion-weighted measurement data with switching of diffusion gradients for diffusion encoding of the measurement data, using a first echo spacing, and a second subsampled set of non-diffusion-weighted measurement data using the first echo spacing are acquired, the first and the second subsampled set of measurement data are supplemented to produce first and second complete sets of measurement data, using calibration data. At least the first calibration data used for supplementing the second subsampled set of measurement data to produce a second complete set of measurement data has been acquired in accordance with the first echo spacing. By supplementing subsampled sets of measurement data with calibration data acquired according to the same echo spacing as the subsampled measurement data to produce complete sets of measurement data, noise signals in the supplemented measurement data are advantageously eliminated.

In a method for simultaneous generation of measurement data of at least two subvolumes of an examination object by means of a slice multiplexing EPI-method, after an RF excitation pulse, at least three navigator signals, but a total of at least one navigator signal per possible polarity and per subvolume to be simultaneously recorded, are recorded in the absence of phase encoding gradients. From the recorded navigator signals, subvolume-specific correction data is determined, which can be used in a reconstruction of image data from acquired raw data for correcting shifts caused by phase errors in the MR raw data.

Suppressing artifacts in MRI image acquisition data includes alternatives to phase cycling by using a Convolutional Neural Network to suppress the artifact-generating echos. A U-NET CNN is trained using phase-cycled artifact-free images for ground truth comparison with received displacement encoded stimulated echo (DENSE) images. The DENSE images include data from a single acquisition with both stimulated (STE) and T1-relaxation echoes. The systems and methods of this disclosure are explained as generating artifact-free images in the ultimate output and avoiding the additional data acquisition needed for phase cycling and shortens the scan time in DENSE MRI.

A magnetic resonance imaging method according to an embodiment is a method for implementing a multi-shot Fast Spin Echo method. The method includes acquiring, for a k-space divided into a plurality of segments with respect to a phase encode direction, one of the segments including a central region of the k-space with one shot, wherein, during the one-shot acquisition for the central region of the k-space, refocus pulses corresponding to a first time period among refocus pulses applied a plurality of times have a flip angle decreasing tendency, and refocus pulses corresponding to a second time period following the first time period among the refocus pulses applied the plurality of times have a flip angle maintaining or increasing tendency.

In a method and system for acquiring measurement data reference data for a phase correction of the measurement data, a RF excitation pulse is provided to excite spins in the object under examination, one or more RF refocusing pulses are provided to refocus the spins excited by the RF excitation pulse, measurement data is acquired by recording echo signals of refocused spins excited by the RF excitation pulse by switching readout gradients that alternate in their polarity, at least two echo signals are recorded while switching readout gradients with different polarity acquire reference data, chronologically between the providing of the RF excitation pulse and the acquisition of the measurement data, and correction data is determined for phase correction of phase errors contained in the measurement data based on the acquired reference data.

A method a for acquiring magnetic resonance data of an object under examination by means of a magnetic resonance system comprises: in an excitation phase, applying an RF excitation pulse; in a wait phase following the excitation phase, applying at least one first RF refocusing pulse after the applied RF excitation pulse according to a first echo spacing; in an acquisition phase following the wait phase, applying at least two further RF refocusing pulses to generate echo signals according to a second echo spacing, wherein the second echo spacing is smaller than the first echo spacing; and reading out the echo signals generated in the acquisition phase as magnetic resonance data from which image data can be reconstructed, wherein in the wait phase at least two spoiler gradients are switched in the readout direction.

A method for correcting concomitant gradient field effects in a magnetic resonance imaging (MRI) system includes determining a plurality of first phase difference measurements between two acquisitions using a plurality of first bipolar gradient waveforms applied to a first gradient coil. A first gradient coil constant is determined based on the plurality of first phase difference measurements and compensatory gradient waveforms are determined based on the first gradient coil constant. The compensatory gradient waveforms are applied to the gradient coils along with target gradient waveforms to compensate for a concomitant gradient field.

Phase-incrementing MRSI (pi-MRSI) method has resolved overlapping biomarker images in the presence of a read-gradient. On a Bruker 9.4T MRI spectrometer, the pi-SEE-HSelMQC sequence was implemented. The choline-selective and lactate CH-selective RF pulses were phase incremented by 10° in opposite signs, synchronized with the phase-encoding steps. The lactate and choline images from a yogurt phantom displayed opposite image offsets without image overlapping. In vivo one-dimensional pi-SEE-HSelMQC CSI images of lactate and choline, acquired from the MDA-MB-231 human breast cancer xenograft in a nude mouse, as well as two-dimensional pi-SEE-HSelMQC imaging of lactate and choline acquired from the PC3 human prostate cancer xenograft in a nude mouse, also had opposite image offsets, shifted away from the spurious residual water signals in the image center. The pi-SEE-HSelMQC method completely suppresses lipid and water with potential clinical applications in disease diagnosis and therapeutic interventions.