Xiaohong Joe Zhou, 62707 Conestoga Rd, Naperville, IL 60563

6369568, Apr 9, 2002

Jun 3, 1999

09/325081

Jingfei Ma - Waukesha WI
Xiaohong Zhou - Houston TX

GE Medical Systems Global Technology Company, LLC - Waukesha WI

G01V 300

324309, 324307, 324314

A prescan process for an MR fast spin echo (FSE) pulse sequence adjusts the phases of the RF excitation pulse and RF refocusing pulses in the FSE pulse sequence to reduce the spatially invariant phase errors (zeroth order). The prescan process also calculates the value of a readout gradient compensation pulse, a phase-encoding gradient compensation pulse and a slice-select gradient compensation pulse to reduce the first order phase shifts along the readout, phase-encoding, and slice-select gradient axes.

6380738, Apr 30, 2002

Dec 22, 1999

09/469864

Xiaohong Zhou - Houston TX

GE Medical Systems Global Technology Company, LLC - Waukesha WI

G01V 300

324309, 324307, 324306

A magnetic resonance (MR) imaging system including a method and apparatus for reducing image artifacts caused by magnet vibration is disclosed herein. The system includes a magnetic field vibration quantification and compensation scheme including quantifying a vibration error component included in the magnetic field configured to acquire k-space data corresponding to an MR image, and correcting the k-space data using the vibration error component. The vibration-induced magnetic field perturbation includes a spatially invariant magnetic field, a spatially linear readout magnetic field gradient, a spatially linear phase-encoding magnetic field gradient, and a spatially linear slice-selection magnetic field gradient. The vibration error component can be at least one of a spatially independent phase error of the spatially invariant magnetic field, a k -space displacement error of the spatially linear readout magnetic field gradient, a k -space displacement error of the spatially linear phase-encoding magnetic field gradient, and a slice-selection error of the spatially linear slice-selection magnetic field gradient.

6469505, Oct 22, 2002

Mar 31, 2000

09/540687

Joseph K. Maier - Milwaukee WI
Xiaohong Zhou - Houston TX
Steven J. Huff - Hartland WI

GE Medical Systems Global Technology Co., LLC - Waukesha WI

G01V 300

324309, 324307

A method and apparatus for correcting ghost artifacts that are related to orthogonal perturbation magnetic fields is disclosed. The technique includes acquiring MR data and an MR reference scan, each in the presence of orthogonal perturbation magnetic fields. However, the region of interest for the MR reference scan is limited to a relatively narrow band within the imaging subject. Preferably, the narrow band is selected in the vicinity of the magnet iso-center and parallel to the readout direction. Alternatively, the narrow band can also be selected in the limited region where the orthogonal perturbation fields are either minimal or constant along the phase encoding direction, and parallel to the readout direction. The selection of the relatively narrow band is accomplished by either spatially saturating surrounding regions, or using a two-dimensional spatially selective RF pulse. Phase correction values can then be calculated from a more accurately defined slope and intercept of the phase of the MR reference scan and used to correct the MR data.

6528998, Mar 4, 2003

Mar 31, 2000

09/540768

Xiaohong Zhou - Houston TX
Joseph K. Maier - Milwaukee WI
Steven J. Huff - Hartland WI

GE Medical Systems Global Technology Co., LLC - Waukesha WI

G01V 300

324309, 324307

A method and apparatus for correcting ghosting artifacts that are related to Maxwell fields and/or other perturbation magnetic fields is disclosed. The method and apparatus includes acquiring MR image n-space data and an MR reference scan, each having perturbation field effects therein. After determining phase correction values from the MR reference scan and reconstructing an MR image using the phase correction values, a projection phase error is calculated from the reconstructed MR image and then subtracted from the reference scan, the result of which is used to determine a new set of phase correction values. The new set of phase correction values is applied to the acquired MR image data to reconstruct a new image. The reconstructed new image can then be reused to calculate a new projection phase error, which again is subtracted from the reference scan data and the process is repeated until an image of desired ghost artifact reduction is achieved.

2012002, Feb 2, 2012

Apr 13, 2010

13/263608

Xiaohong Joe Zhou - Naperville IL, US
Novena A. Rangwala - Chicago IL, US

The Board of Trustees of the University of Illinois - Urbana IL

G01R 33/48

324309

Disclosed are methods for magnetic resonance imaging (MRI) that reduce the appearance of fast spin echo cups artifacts using a slice-titting gradient. In particular, the excited image slice is titted relative to the image slice selected by the refocusing RF pulse.

2013014, Jun 13, 2013

Apr 29, 2011

13/695159

Xiaohong Joe Zhou - Naperville IL, US

G01R 33/44
G01R 33/28

324309

A GRASE-type PROPELLER sequence called Steer-PROP is disclosed. This sequence exploits a serious of steer blips together with rewinding gradient pulse to traverse k-space. Steer-PROP improves the scan time by a factor of 3 or higher compared to FSE-PROPELLER, provides improved robustness to off-resonance effects compared to EPI-PROPELLER, and addresses a long-standing phase correction problem inherent to GRASE based sequences. Steer-PROP also enables intra-blade, inter-blade, and inter-shot phase errors to be separately determined and independently corrected.

6323646, Nov 27, 2001

May 21, 1999

9/316230

Xiaohong Zhou - Houston TX
Joseph K. Maier - Milwaukee WI
Steven J. Huff - Hartland WI
Hammond Glenn Reynolds - Milwaukee WI

General Electric Company - Schenectady NY

G01V 300

324309

A technique is provided for generating images on an MRI system in which errors due to gradient pulses are compensated. The errors are identified in advance, such as in a calibration sequence performed on the MRI system. Receiver phase adjustment and logical gradient error values are derived from the identified error values. The calibration sequence may be a modified version of the MRI imaging sequence used to produce the images. The correction values may be based upon corrections at the center of k-space. The technique is particularly useful in compensating for effects of eddy currents in pulse sequences employing high slew rate gradient pulses, such as diffusion weighted echo planar imaging sequences.

6064205, May 16, 2000

Mar 9, 1999

9/265259

Xiaohong Zhou - Pewaukee WI
Yiping Du - Pewaukee WI
Matthew A. Bernstein - Waukesha WI
Hammond G. Reynolds - Milwaukee WI
Joseph K. Maier - Milwaukee WI
Jason A. Polzin - Lake Mills WI

General Electric Company - Milwaukee WI

G01V 300

324309

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.