Abstract: A system and method for shifting of motion based artifacts in images produced with an magnetic resonance imaging system configured to: select a segment of a plurality of segments comprising a selected number of k-space lines of k-space data for a temporal series and select a time interval from a plurality of time intervals for acquisition. The magnetic resonance imaging system is also configured to acquire N sets of k-space lines comprising every Nth k-space line of the segment for successive 1/N portions of said time interval and repeating the acquiring for successive sets of the N sets of k-space lines and wherein N is an integer greater than one. The acquisition is repeated for each time interval of the plurality of time intervals and for each segment of the plurality of segments. The k-spaced data are reconstructed employing a time-weighted average based on respective time of acquisition of the k-space lines.

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 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 system and method for shifting of motion based artifacts in images produced with an magnetic resonance imaging system configured to: select a segment of a plurality of segments comprising a selected number of k-space lines of k-space data for a temporal series and select a time interval from a plurality of time intervals for acquisition. The magnetic resonance imaging system is also configured to acquire N sets of k-space lines comprising every Nth k-space line of the segment for successive 1/N portions of said time interval and repeating the acquiring for successive sets of the N sets of k-space lines and wherein N is an integer greater than one. The acquisition is repeated for each time interval of the plurality of time intervals and for each segment of the plurality of segments. The k-spaced data are reconstructed employing a time-weighted average based on respective time of acquisition of the k-space lines.

Abstract: A method of synchronizing initiation of a magnetic resonance image (MRI) acquisition to the arrival of a contrast agent in a structure of interest, such as an artery, includes repeatedly performing a first MRI scan until the first MRI scan indicates that the contrast agent has arrived. The first MRI scan acquires a three-dimensional MRI data set from the structure of interest. Preferably, the first MRI scan is a partial MRI scan that produces a low resolution image. Once the first MRI scan indicates that the contrast agent has arrived in the structure of interest, a second MRI scan is performed that acquires a second three-dimensional MRI data set from the structure of interest. The second MRI scan is preferably a full MRI scan that produces a full fidelity image. The manner of data acquisition is advantageously the same for both the first MRI scan and the second MRI scan.

Abstract: A workstation is programmed to operate as an application development system for a medical imaging system. Objects programmed in an object-oriented language are selected from a component library using a visual component assembler which enables them to be dragged from a framework area on a display to a workspace area. Properties of selected components may be edited, and the resulting collection of components may be graphically linked together and saved as an application program.

Abstract: A method of MR imaging using fractional MRI acquisitions to reduce total acquisition time includes the steps of: obtaining a scan-specific partial MRI kx data set fraction and a scan-specific partial MRI ky data set fraction at a first location; acquiring a partial MRI kx data set in k-space along a kx direction, the partial MRI kx data set containing the scan-specific partial MRI kx data set fraction amount of direction data; acquiring a partial MRI ky data set in k-space along a ky direction, the partial MRI ky data set containing the scan-specific partial MRI ky data set faction amount of direction; reconstructing an MR image using the partial MRI kx data set and the partial MRI ky data set; and transmitting information relating to the MR image between the first location and a second location remote from the first location.

Abstract: An MRI system acquires NMR signals and digitizes them at a fixed sample rate. A lower, prescribed sample rate is obtained by fractionally decimating the sampled NMR signals. Fractional decimation is achieved by a combination of zeropadding the sampled NMR signal in the frequency domain and decimating the sampled NMR signal in the time domain.

Abstract: A system and method for phase sensitive MRI reconstruction using partial k-space data to reduce either scan time or echo time, depending on whether partial echo or partial NEX MR data is acquired, that retains phase information and reduces edge blurring in a magnetic resonance image. Phase sensitive partial k-space data reconstruction improves upon the homodyne reconstruction process to estimate and correct for an edge blurring convolution error term in a partial echo or partial NEX data while preserving phase information. The phase sensitive partial k-space reconstruction includes Fourier transforming and filtering the partial k-space data through high and low-pass filters, and a linear combination of both, and estimating a blurring correction term, representative of a convolution error factor, from a portion of the filtered data set.

Abstract: A method is provided for 3-D MR imaging of structure such as a cardiac region of a subject, which is disposed to cyclical motion. The method comprises detecting commencement of each of a succession of motion cycles, and acquiring a set of MR views of the region during each motion cycle. Each view is at a known radial distance from the center of a two-dimensional k-space, and each set includes a view of lowest spatial frequency, which is located proximate to the k-space center. The order in which the views of respective sets are acquired is selected so that the lowest frequency views of respective sets are each acquired at the same specified time, following commencement of their respectively corresponding motion cycles. The views of each set collectively define a segment in the k-space, respective segments being placed in an interleaved spiral or elliptical arrangement with respect to one another.

Abstract: A system to correct edge blurring in an image reconstructed with partial k-space data includes a magnetic resonance imaging system, a computer, and a network. The magnetic resonance imaging system has a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF modulator controlled by a pulse control module to transmit RF signals to an RF coil assembly to acquire MR images.

Abstract: A system and method is disclosed to combine both a fractional echo (k.sub.x) and a fractional NEX (k.sub.y) to reduce acquisition times and echo times in MR imaging. The method uses both zero-filling and homodyne reconstruction to construct concurrent fractional NEX and fractional echo data in a single image while minimizing any blurring effects. The system includes acquiring partial MRI data in the k.sub.x direction and acquiring partial MRI data in the k.sub.y direction. Once a partial echo and a partial NEX are acquired, the missing data is first zero-filled in the k.sub.x direction and Fourier transformed to acquire a full x direction data set. Next, the data is synthesized in the k.sub.y direction using a homodyne reconstruction technique to acquire a full data set in the k.sub.y direction. The full x,y data set can then be used to reconstruct an MR image with reduced acquisition and echo times.

Abstract: A system and method for correcting systematic errors that occur in MR images due to magnetic gradient non-uniformity is disclosed for use with parametric analysis. A GradWarp geometric correction operation is applied in reconstructing quantitative parametric analysis images in regions of gradient non-uniformity. The method includes generating an error map of magnetic gradient strength as a function of distance for an MR image scan and acquiring MR data that contain such systematic errors. The method next includes either calculating a measured diffusion image, a phase difference image, or similar image, based on the acquired MR data, and then calculating a corrected parametric image using the error map and the measured diffusion image, the phase difference image, or other similar parametric image. The method is incorporated into a system having a computer programmed to perform the aforementioned steps and functions.

Abstract: Two methods are disclosed to remove the image artifacts produced by Maxwell terms arising from the imaging gradients in an echo planar imaging pulse sequence. In the first method, the frequency and phase errors caused by the Maxwell terms are calculated on an individual slice basis and subsequently compensated during data acquisition by dynamically adjusting the receiver frequency and phase. In the second method, two linear phase errors, one in the readout direction and the other in the phase-encoding direction, both of which arise from the Maxwell terms, are calculated on an individual-slice basis. These errors are compensated for in the k-space data after data acquisition.

Abstract: An MRI system acquires NMR signals and digitizes them at a fixed sample rate. A lower, prescribed sample rate is obtained by transforming the acquired NMR signal using a weighting function calculated from scan parameters. The transformation includes multiplying by the weighting function and convolving the NMR signal with the complex conjugate of the weighting function.

Abstract: An MRI system produces magnetic field gradients along physical axes during a patient scan. The gradients are specified as logical gradient waveforms in a pulse sequence and these are stored in a logical vector table. A physical vector table is produced by rotating amplitude values in the logical vector table, and the resulting rotated amplitude values are used to calculate the heating in each gradient axis of the MRI system.

Abstract: A method is presented for correcting Maxwell term error artifacts produced by an NMR system during the production of either a phase contrast angiogram or a complex difference angiogram. Phase corrections are made to the reconstructed phase image to eliminate the artifacts. Correction coefficients calculated from the flow encoding magnetic gradient waveforms of the phase contrast pulse sequence are used in a polynomial to calculate a set of phase error corrections. These corrections are then used to adjust the phase at each pixel of the angiogram image.

Abstract: A method is disclosed to remove the image artifacts produced by Maxwell terms arising from the imaging gradients in an echo planar imaging pulse sequence. The frequency and phase errors caused by the Maxwell terms are calculated on an individual slice basis. During the subsequent data acquisition these errors are compensated by dynamically adjusting the receiver frequency and phase.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. Image frames are reconstructed at each sampling of the central k-space region using the temporally nearest samples from the peripheral k-space regions.

Abstract: NMR image data is acquired with velocity encoding gradients applied and both a phase difference image array and a complex difference image array are produced. A flow image is produced from the complex difference image array after it is corrected for spin saturation effects and calibrated using information derived from the phase difference image array. Total blood flow through vessels can be measured from the flow image.