Abstract: A 3D projection reconstruction pulse sequence is employed during a CEMRA dynamic study to acquire a time course series of k-space data sets. Signals from non-vascular voxels are suppressed by reconstructing a corresponding series of low resolution images using the centers of the acquired k-space data sets, and measuring the degree to which the signal behavior of voxels therein differ from a model of unwanted signal. Signals from voxels which do not differ from the model are suppressed and the resulting filtered low resolution images are transformed back to k-space and combined with the originally acquired peripheral k-space data to form complete, filtered k-space data sets from which images may be reconstructed.

Abstract: A calibration procedure is performed prior to an off-axis MR scan to measure the MRI system timing errors in applying a frequency modulation waveform to the system receiver. Phase errors which otherwise occur when performing non-Cartesian scans are either prospectively reduced by offsetting the timing error or retrospectively offset by applying phase corrections to the acquired image data.

Abstract: Acquisition of MR data during a fMRI study employs a hybrid PR pulse sequence to acquire projection views from which multi-slice image frames may be reconstructed that depict the BOLD response to an applied stimulus or performed task. Composite images are reconstructed at each slice using the combined interleaved projection views from all the acquired image frames. The composite images are used to reconstruct the highly undersampled image frames.

Abstract: A fast and efficient method for reconstructing an image from undersampled, parallel MRI data sets acquired with non-Cartesian trajectories includes the calculation of unsampled k-space data from the acquired k-space data and sets of calculated reconstruction coefficients. To reduce the computation time, only a few reference reconstruction coefficients are calculated using a matrix inversion step and the remaining reconstruction coefficients are produced by interpolating between the reference reconstruction coefficients.

Abstract: A method for reconstructing an image from undersampled, parallel MRI data sets acquired with a pulse sequence that samples k-space along radial trajectories includes the synthesis of training k-space data from the acquired data. The training k-space data is produced by reconstructing training images from the fully sampled, central k-space region of the acquired MRI data sets, and the training k-space data is used in a radial GRAPPA image reconstruction method to produce an image frame.

Abstract: A three-dimensional projection reconstruction pulse sequence acquires two half echoes in a steady state free precession (SSFP) scan. A method for combining the two echoes to suppress either fat or water in the reconstructed image is described includes shifting the phase of one echo and combining them in a regridding process used to transform the radial data to a Cartesian grid prior to image reconstruction.

Abstract: A 3D projection reconstruction pulse sequence is employed during a CEMRA dynamic study to acquire a time course series of k-space data sets. Signals from non-vascular voxels are suppressed by reconstructing a corresponding series of low resolution images using the centers of the acquired k-space data sets, and measuring the degree to which the signal behavior of voxels therein differ from a model of unwanted signal. Signals from voxels which do not differ from the model are suppressed and the resulting filtered low resolution images are transformed back to k-space and combined with the originally acquired peripheral k-space data to form complete, filtered k-space data sets from which images may be reconstructed.

Abstract: A magnetic resonance angiogram (MRA) is acquired using a contrast enhancement method in which a series of low resolution NMR images are rapidly acquired during a time resolved phase of the examination in which the contrast bolus makes a first pass through the arteries and veins. Additional, high spatial resolution NMR image data is acquired in a subsequent steady-state phase of the examination. The low resolution NMR image is segmented and masked to depict only arteries, and the central k-space region of this data is combined with the peripheral k-space data portion of the high resolution NMR data to produce one or more images.