In a method and magnetic resonance imaging apparatus having a scanner that for acquires a magnetic resonance dataset, a magnetic resonance sequence is provided to a computer and is converted in the computer into a digital sequence execution signal that includes a target gradient waveform in the form of a time-discrete target gradient signal the computer calculates a pre-GIRF gradient signal by applying a digital pre-emphasis filter to the target gradient signal. The computer transmits the pre-GIRF gradient signal to the magnetic resonance system scanner and) the scanner executes the digital sequence execution signal containing the pre-GIRF gradient signal in order to acquire magnetic resonance raw data.

In one embodiment, an MRI apparatus includes a gradient coil, a receiving circuit, and processing circuitry. The gradient coil is configured to superimpose a gradient magnetic field on a static magnetic field. The receiving circuit is configured to receive an MR (magnetic resonance) signal from an object placed in the gradient magnetic field. The processing circuitry is configured to estimate time variation of an MR (magnetic resonance) frequency during a sampling period of the MR signal based on waveform data of a gradient current applied to the gradient coil, perform correction on a frequency or phase of the MR signal received by the receiving circuit based on the estimated time variation of the MR frequency during the sampling period, and reconstruct an image by using the MR signal subjected to the correction.

In a method for operating an MRI device, image data is acquired using a spin echo sequence with an additional readout per pulse train for acquiring correction data. By comparing subsequent correction data of later pulse trains to reference data acquired during a first pulse train of the sequence a difference indicating a parameter shift is determined. A corresponding compensation is then automatically determined in dependence on the difference and is applied to a set of predetermined parameters for at least a respective next pulse train and/or to the image data acquired in at least a respective next pulse train of the sequence.

The invention provides for a medical imaging system (100, 300). The execution of the machine executable instructions (110) causes a processor (102) to: receive (200) multiple diffusion weighted images (112) of a subject (318), wherein the multiple diffusion weighted images each have an assigned b-value, wherein the multiple diffusion weighted images each have an assigned diffusion weighting direction, wherein for a region of interest (309) there is at least one corresponding voxel (506) in each of the multiple diffusion weighted images; construct (202) a set of equations (114) for each of the at least one corresponding voxel, wherein the set of equations is constructed from an apparent diffusion equation for the assigned diffusion weighting direction of each of the multiple diffusion weighted images; solve (204) the set of equations for each voxel for the b.sub.0 value as an optimization; and construct (206) a b.sub.0 image using the b.sub.0 value for each voxel.

Systems and methods for generating a gradient waveform for use by a low-field MRI system to generate a gradient magnetic field are provided herein. The gradient waveform can be determined using first information indicative of the gradient waveform and second information indicative of hardware constraints of the low-field MRI system including a maximum voltage of the gradient power amplifier, a maximum slew rate of the gradient coil, a resistance of the gradient coil, and an inductance of the gradient coil. In some embodiments, the gradient waveform can be a trapezoidal gradient waveform determined to have a non-linear ramp-up portion and/or a non-linear ramp-down portion.

Systems and methods for generating a gradient waveform for use by a low-field MRI system to generate a gradient magnetic field are provided herein. The gradient waveform can be determined using first information indicative of the gradient waveform and second information indicative of hardware constraints of the low-field MRI system including a maximum voltage of the gradient power amplifier, a maximum slew rate of the gradient coil, a resistance of the gradient coil, and an inductance of the gradient coil. In some embodiments, the gradient waveform can be a trapezoidal gradient waveform determined to have a non-linear ramp-up portion and/or a non-linear ramp-down portion.

A system and method is provided for acquisition of magnetic resonance fingerprinting (“MRF”) data that includes determining a non-locally sequential sampling pattern for a Cartesian grid of k-space, performing a series of sequence blocks using acquisition parameters that vary between sequence blocks to acquire MRF data from a subject using the Cartesian grid of k-space and the determined non-locally sequential sampling pattern, assembling the MRF data into a series of signal evolutions, comparing the series of signal evolutions to a dictionary of known signal evolutions to determine tissue properties of the subject, and generating a report indicating the tissue properties of the subject.

In a method and magnetic resonance (MR) apparatus for reducing artifacts in an image dataset reconstructed from MR raw data that were acquired by radial sampling using different coil elements, for each of at least some of the coil elements, exclusion information is determined that identify MR data from that coil element that are responsible for at least one artifact, by a comparison of a sensitivity map, which defines a spatial reception capability of that coil element, with at least one comparison dataset obtained from at least a portion of the MR data from that coil element. At least the MR data identified from the exclusion information are excluded from the reconstruction of the image dataset.

In one embodiment, an MRI apparatus includes: a scanner that is provided with at least an RF coil and a gradient coil and is configured to acquire a magnetic resonance (MR) signal emitted from an object in response to applications of an RF pulse outputted from the RF coil and a gradient magnetic field generated by the gradient coli; and processing circuitry configured to reconstruct a diagnostic image of the object based on the MR signal, generate distortion correction data for correcting a non-linear characteristic of the gradient magnetic field to a linear characteristic that is defined by gradient magnetic field strength at a correction position away from a magnetic field center of the gradient coil and distance from the magnetic field center to the correction position, and correct the diagnostic image by using the distortion correction data.

A magnetic resonance device comprising a gradient coil assembly having gradient coils is described. The gradient coils are supported by at least one cylindrical coil carrier for generating gradient fields. As part of the gradient coil assembly, at least one vibration sensor is provided for measuring vibrations of the gradient coil assembly at least in a radial direction of oscillation.