General Electric Company

Ge Medical Systems Global Technology, LLC

Bryan James Mock

Frederick Joseph Frigo

Richard Scott Hinks

Xiaoli Zhao

Bruce David Collick

R Scott Hinks

Tejaswini Shubhachint

Charles R Michelich

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.

Method and apparatus of echo planar imaging with real-time determination of phase correction coefficients

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.

Method and system for image artifact reduction using nearest-neighbor phase correction for echo planar imaging

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.

Method and system of MR imaging with variable readout gradient filtering

A technique for calculating actual b-values in a diffusion weighted magnetic resonance imaging system and of adjusting the observed b-value until it is within a tolerance range of the prescribed b-value. A diffusion weighted image with the desired diffusion sensitivity may then be produced. Calculation of the actual b-value is accomplished by integrating the linear segments of the gradient waveform. Adjustment of observed b-value is accomplished by initially scaling the diffusion lobe amplitude and comparing a recalculated b-value to the prescribed b-value. Additional adjustment is provided by means of a numeric search iteratively performed until the recalculated b-value is within tolerance of the prescribed b-value.

B-value calculation and correction using a linear segment gradient waveform model

A technique is described for correcting phase errors in a bipolar readout gradient MRI imaging sequence, such as an EPI examination. The technique employs alternating sets of oscillating readout gradient pulses. Each readout pulse train has a polarity which is inverted with respect to an immediately preceding and an immediately succeeding readout sequence. The collected data then incorporates both image data and data which is used to correct for phase errors. Following data acquisition, correction factors may be determined from the k-space frames for correction of successive k-space data. K-space frames may be reformatted to inherently correct for phase errors, followed by combination of hybrid k-space data frames to obtain a corrected image.

Method and apparatus for reducing artifacts in echo planar imaging

A technique is described for correction of phase errors in bipolar readout gradient examination sequences, such as EPI pulse sequences. The technique employs short reference pulse sequences associated with each readout pulse train. Reference data is collected for positive and negative lobes of the reference sequence. Each reference sequence is employed to estimate a phase error of an associated readout sequence. Data collected in the readout sequence is then corrected based upon the estimated errors. Phase errors resulting from changes in scan orientation are thereby corrected for each frame of k-space data without significantly increasing the data acquisition time.

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Lake Mills, WI, United States of America

Bryan James Mock