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 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: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus is disclosed for immobilizing a patient's head within an MRI headcoil to avoid the use of imaging enhancements that compensate for patient movement. The apparatus includes a bite plate having a dental impression of the particular patient at one end, and at the other end, the bite plate is attached to a mounting bracket assembly. The mounting bracket assembly is rigidly attached to the MRI headcoil. The mounting bracket assembly includes a main bracket, an intermediary bracket, and a clamping plate. The bite plate is adjustably mounted to the intermediary bracket, which in turn is adjustably mounted to the main bracket to provide both approximate adjustments and precise adjustments, respectively. The clamping plate attaches the mounting bracket assembly to at least one rung of the headcoil.