Abstract: A method for generating a magnetic resonance (MR) image includes applying a pulse sequence including a quadratic field gradient. A first k-space data set is acquired from each of a plurality of RF coils where each first k-space data set including uniformly undersampled data. A randomly undersampled k-space data set is generated for each RF coil from the first k-space data set. A compressed sensing reconstruction technique is applied to the randomly undersampled k-space data set of each RF coil to generate a second k-space data set for each RF coil where each second k-space data set including uniformly undersampled data. A phase scrambling reconstruction technique is applied to the second k-space data set of each RF coil to generate a low resolution coil image for each RF coil. A MR image is generated by applying a parallel imaging technique to the low resolution coil image and second k-space data set for each RF coil.

Abstract: A computer is programmed to acquire calibration data from a calibration scan, the calibration data configured to characterize high order eddy current (HOEC) generated magnetic field error of an imaging system. The computer is also programmed to process the calibration data to generate a plurality of basis coefficients and a plurality of time constants and to calculate a plurality of basis correction coefficients based on the plurality of basis coefficients, the plurality of time constants, and gradient waveforms in a given pulse sequence. The computer is further programmed to execute a diffusion-weighted imaging scan that comprises application of a DW-EPI pulse sequence to acquire MR data from an imaging subject and reconstruction of an image based on the acquired MR data. The computer is also programmed to apply HOEC-generated magnetic field error correction during application of the DW-EPI pulse sequence configured to reduce HOEC-induced distortion in the reconstructed image.

Abstract: A method for generating a magnetic resonance image includes acquiring a first k-space data set from each of a plurality of RF coils. The first k-space data set includes calibration data and randomly undersampled data. For each RF coil, a fully randomly sampled k-space data set is generated by removing a portion of the calibration data. A compressed sensing reconstruction technique is applied to the fully randomly sampled k-space data set to generate an aliased image, which is used to generate a uniformly undersampled k-space data set. A second k-space data set is generated by inserting the portion of the calibration data and a parallel imaging reconstruction technique is applied to the second k-space data set to synthesize unacquired data. The second k-space data set and the synthesized data are combined to generate a complete k-space data set for the RF coil.

Abstract: A system and method is disclosed for eliminating localized fluctuation artifacts caused by fat signal contamination in MR images, the system includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images, and a computer programmed to apply a spectral-spatial fat saturation pulse, apply a slice selection gradient pulse, acquire imaging data of an imaging slice of interest, and generate an image.

Abstract: A method, system, and apparatus including a magnetic resonance imaging (MRI) apparatus that includes an MRI system having a plurality of gradient coils, a radio-frequency (RF) transceiver system, an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly, and a computer. The computer is programmed to implement a spin echo sequence to acquire magnetic resonance (MR) data, where the spin echo sequence includes an excitation RF pulse and at least one refocusing pulse per repetition time (TR) of the excitation pulse. The computer is also programmed to transmit at least two component RF pulses in parallel channels during implementation of the spin echo sequence to produce a first refocusing RF pulse and programmed to reconstruct an image from spin echo sequence image data.

Abstract: A computer is programmed to acquire calibration data from a calibration scan, the calibration data configured to characterize high order eddy current (HOEC) generated magnetic field error of an imaging system. The computer is also programmed to process the calibration data to generate a plurality of basis coefficients and a plurality of time constants and to calculate a plurality of basis correction coefficients based on the plurality of basis coefficients, the plurality of time constants, and gradient waveforms in a given pulse sequence. The computer is further programmed to execute a diffusion-weighted imaging scan that comprises application of a DW-EPI pulse sequence to acquire MR data from an imaging subject and reconstruction of an image based on the acquired MR data. The computer is also programmed to apply HOEC-generated magnetic field error correction during application of the DW-EPI pulse sequence configured to reduce HOEC-induced distortion in the reconstructed image.

Abstract: A computer is programmed to acquire calibration data from a calibration scan, the calibration data configured to characterize high order eddy current (HOEC) generated magnetic field error of an imaging system. The computer is also programmed to process the calibration data to generate a plurality of basis coefficients and a plurality of time constants and to calculate a plurality of basis correction coefficients based on the plurality of basis coefficients, the plurality of time constants, and gradient waveforms in a given pulse sequence. The computer is further programmed to execute a diffusion-weighted imaging scan that comprises application of a DW-EPI pulse sequence to acquire MR data from an imaging subject and reconstruction of an image based on the acquired MR data. The computer is also programmed to apply HOEC-generated magnetic field error correction during image reconstruction configured to reduce HOEC-induced distortion in the reconstructed image.

Abstract: A system and method for multi-spectral MR imaging near metal include a computer programmed to calculate an MR pulse sequence comprising a plurality of RF pulses configured to excite spins in an imaging object and comprising a plurality of volume selection gradients and determine a plurality of distinct offset frequency values. For each respective determined offset frequency value, the computer is programmed to execute the MR pulse sequence having a central transmit frequency and a central receive frequency of the MR pulse sequence set to the respective determined offset frequency value. The computer is also programmed to acquire a three-dimensional (3D) MR data set for each MR pulse sequence execution and generate a composite image based on data from each of the acquired 3D MR data sets.

Abstract: A system and method is disclosed for eliminating localized fluctuation artifacts caused by fat signal contamination in MR images, the system includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images, and a computer programmed to apply a spectral-spatial fat saturation pulse, apply a slice selection gradient pulse, acquire imaging data of an imaging slice of interest, and generate an image.

Abstract: Techniques for designing RF pulses may be configured to produce improved magnitude profiles of the resulting magnetization by relaxing the phase constraint and optimizing the phase profiles. In one embodiment, a spinor-based, optimal control, optimal phase technique may be used to design arbitrary-tip-angle (e.g., large and small tip angle) RF pulses (both parallel transmission and single channel). In another embodiment, small tip angle RF pulses (both parallel transmission and single channel) may be designed using a small-tip-angle (STA) pulse design without phase constraint that is formulated as a parameter optimization problem.

Abstract: A method, system, and apparatus including a magnetic resonance imaging (MRI) apparatus that includes an MRI system having a plurality of gradient coils, a radio-frequency (RF) transceiver system, an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly, and a computer. The computer is programmed to implement a spin echo sequence to acquire magnetic resonance (MR) data, where the spin echo sequence includes an excitation RF pulse and at least one refocusing pulse per repetition time (TR) of the excitation pulse. The computer is also programmed to transmit at least two component RF pulses in parallel channels during implementation of the spin echo sequence to produce a first refocusing RF pulse and programmed to reconstruct an image from spin echo sequence image data.

Abstract: Coil sensitivity of a receive coil to a gradient null location is measured and, from the measurements, a coil calibration value is determined and used to modify the MR data acquired with that receive coil to reduce the adverse effects of gradient nulling on MR images. Coil sensitivity values are determined for each coil of a coil array and the data for each coil is respectively weighted. An image that is substantially free of gradient null artifacts or ghosting is then reconstructed from the weighted data.

Abstract: A system and method for multi-spectral MR imaging near metal include a computer programmed to calculate an MR pulse sequence comprising a plurality of RF pulses configured to excite spins in an imaging object and comprising a plurality of volume selection gradients and determine a plurality of distinct offset frequency values. For each respective determined offset frequency value, the computer is programmed to execute the MR pulse sequence having a central transmit frequency and a central receive frequency of the MR pulse sequence set to the respective determined offset frequency value. The computer is also programmed to acquire a three-dimensional (3D) MR data set for each MR pulse sequence execution and generate a composite image based on data from each of the acquired 3D MR data sets.

Abstract: An apparatus and method for MR imaging in inhomogeneous magnetic fields includes acquisition of a plurality of three-dimensional (3D) MR data sets, each data set having a central transmit frequency and a central receive frequency set to a frequency offset that is distinct for each 3D MR data set. A composite image is generated based on the plurality of 3D MR data sets.

Abstract: Techniques for designing RF pulses may be configured to produce improved magnitude profiles of the resulting magnetization by relaxing the phase constraint and optimizing the phase profiles. In one embodiment, a spinor-based, optimal control, optimal phase technique may be used to design arbitrary-tip-angle (e.g., large and small tip angle) RF pulses (both parallel transmission and single channel). In another embodiment, small tip angle RF pulses (both parallel transmission and single channel) may be designed using a small-tip-angle (STA) pulse design without phase constraint that is formulated as a parameter optimization problem.

Abstract: A system and method are provided for adjusting RF pulses and gradient waveforms to reduce B1 field magnitude in MR imaging sequences. When an RF pulse is presented which has a high amplitude segment that would exceed a maximum B1 magnitude, the system and method provided herein can apply a variable slew rate design technique. A slew rate of at least one gradient waveform can be varied to reduce a B1 field magnitude during transmission of the high amplitude segment of the RF pulse. By controlling the slew rate of gradient waveforms for non-Cartesian k-space trajectories according to a calculated maximum allowable slew rate function, embodiments of the system and method can, in effect, reduce gradient amplitude.

Abstract: A system and method are provided for designing RF pulses which have improved magnetization profiles. By utilizing an optimal control approach as an alternative to, or in combination with, non-iterative approximations, RF pulses generated by the system and method described herein will exhibit less deviation from that of “ideal” Bloch solutions. Consequently, the magnetization profiles produced by the RF pulses generated by the system and method described herein will be closer to the desired profiles. In addition, limitations of non-iterative approximations, such as maximum tip angle limits and linearity constraints, can be avoided.

Abstract: A system and method for reducing the scan time of an MR imaging system using a data acquisition technique that combines partial Fourier acquisition and compressed sensing includes a computer programmed to acquire a partial MR data set in k-space along a phase encoding direction, the data set having missing data in the phase encoding direction due to the omission of phase encoding steps. The computer is further programmed to generate an estimate of a reconstructed image, compensate the partial MR data set for the missing data, and reconstruct an MR image by iteratively minimizing the total squared difference between the k-space data of the estimate of the reconstructed image and the measured k-space data of the compensated partial MR data set.

Abstract: Variable-density (VD), sequentially-interleaved sampling of k-space coupled with the acquisition of reference frames of data is carried out to improve spatiotemporal resolution, image quality, and signal-to-noise ratio (SNR) of dynamic images. In one example, ktSENSE is implemented with a non-static regularization image, such as that provided by RIGR or similar technique, to acquire and reconstruct dynamic images. The integration of ktSENSE and RIGR, for example, provides dynamic images with higher spatiotemporal resolution and lower image artifacts compared to dynamic images acquired and reconstructed using ktSENSE alone.

Abstract: An apparatus and method for MR imaging in inhomogeneous magnetic fields includes acquisition of a plurality of three-dimensional (3D) MR data sets, each data set having a central transmit frequency and a central receive frequency set to a frequency offset that is distinct for each 3D MR data set. A composite image is generated based on the plurality of 3D MR data sets.