Abstract: Methods and systems are provided for hybrid slice encoding. In one embodiment, a method for magnetic resonance imaging comprises, during a scan with a pulse sequence, sampling k-space linearly for a predetermined number of echoes, and sampling k-space centrically for remaining echoes of the pulse sequence. In this way, blurriness along the slice direction may be reduced for 3D fast spin echo imaging.

Abstract: Methods and systems are provided for hybrid slice encoding. In one embodiment, a method for magnetic resonance imaging comprises, during a scan with a pulse sequence, sampling k-space linearly for a predetermined number of echoes, and sampling k-space centrically for remaining echoes of the pulse sequence. In this way, blurriness along the slice direction may be reduced for 3D fast spin echo imaging.

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: An apparatus and method include a computer programmed to implement a scan sequence configured to elicit scan data, wherein the scan sequence comprises an echo planar imaging (EPI) sequence configured to elicit the image data and to acquire the scan data. The computer is also programmed to manipulate the scan data to determine a first plurality of phase errors in the image data responsible for a Nyquist ghost, wherein the manipulated scan data is free of navigator echo data, remove the first plurality of phase errors from the image data, and reconstruct an image based on the image data having the first plurality of phase errors removed therefrom.

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: An apparatus and method include a computer programmed to implement a scan sequence configured to elicit scan data, wherein the scan sequence comprises an echo planar imaging (EPI) sequence configured to elicit the image data and to acquire the scan data. The computer is also programmed to manipulate the scan data to determine a first plurality of phase errors in the image data responsible for a Nyquist ghost, wherein the manipulated scan data is free of navigator echo data, remove the first plurality of phase errors from the image data, and reconstruct an image based on the image data having the first plurality of phase errors removed therefrom.

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: The present invention includes a technique for use with magnetic resonance imaging that includes the application of a non-linear, higher-order gradient field in the presence of a moving object to be scanned. MR data is acquired as the object moves through the non-linear gradient field. Resulting images are contiguous and do not require the patching together of data in either k-space or image space and result in an image with expanded FOV in a longitudinal direction of the moving object.

Abstract: A technique for reconstructing a corrected MR image from MR images distorted by foreign object induced magnetic fields includes locating a foreign object in a subject and defining a localized area of a field of view about the foreign object where a magnetic field distortion adversely affects a first magnetic distortion correction technique. The first magnetic distortion correction technique is applied to the field of view other than in the localized area. A second magnetic distortion correction technique is applied to the localized area and the results of the application of the first and second magnetic distortion correction techniques are combined. An image is reconstructed based on the results of the application of the first and second magnetic distortion correction techniques.

Abstract: A technique for reconstructing a corrected MR image from MR images distorted by foreign object induced magnetic fields includes locating a foreign object in a subject and defining a localized area of a field of view about the foreign object where a magnetic field distortion adversely affects a first magnetic distortion correction technique. The first magnetic distortion correction technique is applied to the field of view other than in the localized area. A second magnetic distortion correction technique is applied to the localized area and the results of the application of the first and second magnetic distortion correction techniques are combined. An image is reconstructed based on the results of the application of the first and second magnetic distortion correction techniques.

Abstract: The present invention provides an apparatus and method of phase correction whereby changes in phase characteristics are measured during data acquisition and, accordingly, phase correction parameters that are applied during image reconstruction are updated in real-time. This adaptive and dynamic phase correction reduces variability in image fidelity during the course of long MR scans, such as EPI scans, and provides consistent artifact reduction during the course of an MR scan.

Abstract: A pulse sequence is defined to acquire calibration MR data used to characterize on-axis and cross-axis eddy currents resulting from gradient pulses used to spatially encode MR data. The amplitudes and time constants of those eddy currents can then be measured and used to guide calibration of an MRI system to reduce image artifacts.

Abstract: A nearest neighbor phase correction technique is implemented to reduce image artifacts due to phase errors in data acquired in an EPI scan. Image quality for EPI applications, such as DWI, DTI, and fMRI, is improved.

Abstract: A method and system of MR imaging where variable readout gradient filtering (VRGF) is carried out after MR data acquired during gradient field transitions has been phase-corrected. Thus, phase errors can be removed prior to VRGF re-sampling of the MR data. As such, image artifacts due to phase errors can be reduced, improving image fidelity and reducing ghosting especially for poorly calibrated systems.

Abstract: The present invention includes a technique for use with magnetic resonance imaging that includes the application of a non-linear, higher-order gradient field in the presence of a moving object to be scanned. MR data is acquired as the object moves through the non-linear gradient field. Resulting images are contiguous and do not require the patching together of data in either k-space or image space and result in an image with expanded FOV in a longitudinal direction of the moving object.

Abstract: A phase correction method for MR devices includes collecting non-phase encoded reference data, calculating phase coefficients, and then phase correcting the regular phase-encoded image dataset based on these coefficients. The phase correction method can be used for two dimensional or three dimensional FSE imaging and variants thereof. As the method is conducted after signal acquisition, it is considered a retrospective phase correction.

Abstract: The present invention includes a technique for use with magnetic resonance imaging that includes the application of a non-linear, higher-order gradient field in the presence of a moving object to be scanned. MR data is acquired as the object moves through the non-linear gradient field. Resulting images are contiguous and do not require the patching together of data in either k-space or image space and result in an image with expanded FOV in a longitudinal direction of the moving object.

Abstract: A technique is provided for characterizing and correcting for instabilities or variations in a magnet system of an MRI scanner. The technique makes use of a navigator pulse to read out navigator echo data in the absence of phase encode, or with phase encode effects rewound. The navigator data is used to characterize several potential effects of magnet system instabilities or variations, such as zeroth order phase shifts, first order (linear) phase shifts, bulk position shifts, and amplitude effects. The effects of the instabilities can be used, then, to correct image data acquired during an examination.

Abstract: Monitor signals are acquired in an interleaved manner during a scan with an MRI system. Frequency changes caused by variations in the polarizing field B0 are measured using the monitor signals, and these measured frequency changes are employed to compensate image data acquired during the scan. Electrical currents are produced in a set of shim coils that shim the polarizing field B0 in the immediate vicinity proximal to the monitor coil.

Abstract: A plurality of magnetic field induction coils and a radio frequency (RF) detection coil are supported by a frame which is inserted into the bore of an MRI system to detect magnetic fields produced by gradient pulses and RF pulses produced during a scan. The detected magnetic fields are processed to produce gradient waveforms and RF pulse waveforms that are displayed to the user.