Abstract: An MRI system produces a three-dimensional image by acquiring NMR signals that fully sample a central region of k-space and partially sample peripheral k-space as a set of asymmetric radial sectors. The NMR signals are acquired with a plurality of receive channels and coils. An image is reconstructed using a homodyne reconstruction combined with SENSE processing.

Abstract: The present invention is a coil array for an MRI system that is designed to improve 2D accelerated imaging of an object having significantly different fields of view in two phase-encoding directions. This is achieved by having a first set of coil elements whose sizes are tuned to optimize acceleration along a first phase-encoding direction and a second set of coil elements whose sizes are tuned to optimize acceleration along a second-phase encoding direction. Images acquired in accordance with the present invention exhibit improved signal to noise ratio at a given acceleration factor when compared to images acquired using a traditional MR coil array.

Abstract: A method of producing a series of vasculature images over an extended field of view (FOV) larger than an FOV of an MRI system includes acquiring initial time-resolved image data from the vasculature and, during the acquiring process, reconstructing, in substantially real-time, a series of three-dimensional (3D) tracking images of the initial portion of the vasculature illustrating a current position of a contrast bolus in the vasculature as the contrast bolus passes through the initial portion of the vasculature. Based on a current position of the contrast bolus, the subject is moved to a subsequent imaging station to acquire subsequent time-resolved image data and reconstruct subsequent 3D tracking images of subsequent portions of the vasculature. This process is repeated and then an image is assembled that extends over the extended FOV using the initial time-resolved image data and the subsequent time-resolved image data.

Abstract: An MRI system produces a three-dimensional image by acquiring NMR signals that fully sample a central region of k-space and partially sample peripheral region of k-space. Specifically, k-space is arranged as a three-dimensional (3D) Cartesian grid of points that is divided into a central region of k-space and a peripheral region of k-space. Points are selected in k-space within a plurality of radial vanes that extend radially outward from the central region of k-space through the peripheral region of k-space as viewed in a plane sampled by two phase encoding gradients to create a plurality of gaps between the radial vanes that is substantially a factor of N times greater in area than the radial vanes. Using an MRI system having arrays of RF receiver coils, NMR signals are acquired from a subject to fully sample the central region of the 3D k-space and undersample the peripheral region of k-space by only sampling k-space within the plurality of radial vanes.

Abstract: A radio frequency (RF) coil array configured for use with a magnetic resonance imaging (MRI) system and that includes coil elements with a skewed coil geometry is provided. The coil elements are skewed with respect to a given direction, such as the slice-encoding direction of an MRI system, such that a variation in spatial sensitivity along that direction is provided. This spatial sensitivity variation allows for parallel imaging acceleration along the direction of the variation, which provides improved performance over standard rectangular geometries in performing acceleration along the slice-encode direction for three-dimensional axial acquisitions.

Abstract: A method for producing an image indicative of the time-of-arrival of contrast agent in a tissue of interest is provided. More specifically, a time-of-arrival is calculated for each voxel location in a time series of magnetic resonance (MR) images. The accuracy of the time-of-arrival presentation is enhanced when the underlying MR image acquisition is consistent, is done with compact sampling of the k-space center, has minimal temporal footprint for each image, and has a negligible anticipation artifact. The time-of-arrival presentation can be further enhanced by the suppression of signals from background tissue by using, for example, thresholding or by conversion of the time-of-arrival information into a color scale.

Abstract: The present invention provides an MRI system for imaging of a subject over extended field-of-view (FOV) that employs both accelerated data acquisition, which is employed while the subject is stationary, and traditional data acquisition, which is employed while the subject is moved through the MRI system. This approach provides improved spatial resolution and time efficiency compared to traditional extended FOV imaging techniques.

Abstract: The present invention is a coil array for an MRI system that is designed to improve 2D accelerated imaging of an object having significantly different fields of view in two phase-encoding directions. This is achieved by having a first set of coil elements whose sizes are tuned to optimize acceleration along a first phase-encoding direction and a second set of coil elements whose sizes are tuned to optimize acceleration along a second-phase encoding direction. Images acquired in accordance with the present invention exhibit improved signal to noise ratio at a given acceleration factor when compared to images acquired using a traditional MR coil array.

Abstract: An improved self-calibration method for accelerated magnetic resonance imaging (MRI) using inversion recovery pulse sequences allows calibration data for determining coil sensitivity profiles to be acquired by employing a calibration pulse sequence within the delay time of an inversion recovery pulse sequence. The calibration pulse sequence includes a constrained number of calibration pulses having small flip angles so that acceptable longitudinal magnetization recovery is provided.

Abstract: MRA data is acquired from an extended field of view by translating the patient through the bore of the MRI system as three-dimensional MRA data sets are acquired and time-resolved images reconstructed. The leading edge of a contrast bolus can be tracked in these images and parameters such as bolus velocity and bolus arrival time can be calculated to provide functional information in addition to anatomical information. Temporal resolution is improved by undersampling peripheral k-space and sampling the center of k-space at a higher temporal rate.

Abstract: An MRI system produces a three-dimensional image by acquiring NMR signals that fully sample a central region of k-space and partially sample peripheral region of k-space. Specifically, k-space is arranged as a three-dimensional (3D) Cartesian grid of points that is divided into a central region of k-space and a peripheral region of k-space. Points are selected in k-space within a plurality of radial vanes that extend radially outward from the central region of k-space through the peripheral region of k-space as viewed in a plane sampled by two phase encoding gradients to create a plurality of gaps between the radial vanes that is substantially a factor of N times greater in area than the radial vanes. Using an MRI system having arrays of RF receiver coils, NMR signals are acquired from a subject to fully sample the central region of the 3D k-space and undersample the peripheral region of k-space by only sampling k-space within the plurality of radial vanes.

Abstract: MRA data is acquired from a large, longitudinal region of interest by translating the patient through the more limited longitudinal FOV of the MRI system as a three-dimensional MRA data set are acquired. Patient table movement is controlled to track a bolus of contrast agent as it passes through the region of interest. A seamless image of the entire region of interest is reconstructed after correcting the phase of acquired MRA data to reduce the signal falloff at abutting longitudinal FOVs. Phase corrections are determined from the central DC views acquired during the scan.

Abstract: An MRI system produces a three-dimensional image by acquiring NMR signals that fully sample a central region of k-space and partially sample peripheral k-space as a set of asymmetric radial sectors. The NMR signals are acquired with a plurality of receive channels and coils. An image is reconstructed using a homodyne reconstruction combined with SENSE processing.

Abstract: MRA data is acquired from a large region of interest by translating the patient through the bore of the MRI system as a three-dimensional MRA data set are acquired. The pulse sequence is altered during the scan to change the lateral FOVL of the acquired image to better match the size of the region of interest along its length. Patient table movement is controlled to track a bolus of contrast agent as it passes through the region of interest. A seamless image of the entire region of interest is reconstructed after the acquired data is resampled in regions where the lateral FOVL is altered.

Abstract: The present invention includes a method and apparatus to correct for gradient field distortions. The invention is particularly applicable in moving table imaging where a single extended image is desirable. The invention includes acquiring MR data in motion in the presence of gradient non-linearities, transforming the MR data acquired into the image domain, and then applying a warping correction function to the transformed MR data. The warp-corrected MR data is then corrected for motion induced during the MR acquisition. The data may be acquired point-by-point, line-by-line, or another sub-portion of the entire MR data acquired, and processed to minimize the amount of motion correction needed. Based on table velocity or acquisition sequence applied, the data is partitioned based on a common motion correction factor, and after correcting for motion, the data is accumulated to build up a final image.

Abstract: MRA data is acquired from a large region of interest by translating the patient through the bore of the MRI system as a three-dimensional MRA data set are acquired. Patient table movement is controlled to track a bolus of contrast agent as it passes through the region of interest. Fluoroscopic images may be acquired during the scan to enable accurate bolus tracking. A seamless image of the entire region of interest is reconstructed.

Abstract: A method for the simultaneous acquisition of data from two transmit/receive “birdcage” coils is described. The coils are individually RF shielded, making them insensitive to signals generated outside of each coil's volume. Each coil is designed for imaging one leg, and when used together, both legs are imaged simultaneously. In coronal or axial orientations, a small FOV around each leg can be imaged without aliasing. This results in a two-fold scan time reduction compared to a large FOV acquisition with the same spatial resolution.

Abstract: MRA data is acquired from an extended field of view by translating the patient through the bore of the MRI system as three-dimensional MRA data sets are acquired and time-resolved images reconstructed. The leading edge of a contrast bolus can be tracked in these images and parameters such as bolus velocity and bolus arrival time can be calculated to provide functional information in addition to anatomical information. Temporal resolution is improved by undersampling peripheral k-space and sampling the center of k-space at a higher temporal rate.

Abstract: The present invention includes a method and apparatus to correct for gradient field distortions. The invention is particularly applicable in moving table imaging where a single extended image is desirable. The invention includes acquiring MR data in motion in the presence of gradient non-linearities, transforming the MR data acquired into the image domain, and then applying a warping correction function to the transformed MR data. The warp-corrected MR data is then corrected for motion induced during the MR acquisition. The data may be acquired point-by-point, line-by-line, or another sub-portion of the entire MR data acquired, and processed to minimize the amount of motion correction needed. Based on table velocity or acquisition sequence applied, the data is partitioned based on a common motion correction factor, and after correcting for motion, the data is accumulated to build up a final image.

Abstract: The present invention includes a method and apparatus to correct for gradient field distortions. The invention is particularly applicable in moving table imaging where a single extended image is desirable. The invention includes acquiring MR data in motion in the presence of gradient non-linearities, transforming the MR data acquired into the image domain, and then applying a warping correction function to the transformed MR data. The warp-corrected MR data is then corrected for motion induced during the MR acquisition. The data may be acquired point-by-point, line-by-line, or another sub-portion of the entire MR data acquired, and processed to minimize the amount of motion correction needed. Based on table velocity or acquisition sequence applied, the data is partitioned based on a common motion correction factor, and after correcting for motion, the data is accumulated to build up a final image.