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    SYSTEMS AND METHODS OF MEASURING AND CORRECTING EFFECTS OF CONCOMITANT FIELDS IN A MAGNETIC RESONANCE SYSTEM
    1.
    发明公开
    SYSTEMS AND METHODS OF MEASURING AND CORRECTING EFFECTS OF CONCOMITANT FIELDS IN A MAGNETIC RESONANCE SYSTEM 审中-公开

    公开(公告)号：US20240241204A1

    公开(公告)日：2024-07-18

    申请号：US18156127

    申请日：2023-01-18

    申请人： GE PRECISION HEALTHCARE LLC

    发明人： Seung-Kyun Lee ,  Afis Ajala

    IPC分类号： G01R33/565

    CPC分类号： G01R33/56518 ,  A61B5/055 ,  G01R33/56536

    摘要： A method for measuring concomitant fields in a magnetic resonance (MR) system is provided. The method includes applying a measurement pulse sequence in a plurality of acquisitions. Applying the measurement pulse sequence further includes applying a first bipolar gradient pulse in a first acquisition, applying a second bipolar gradient pulse in reverse polarities from the first bipolar gradient pulse in a second acquisition, and applying the measurement pulse sequence without a bipolar gradient pulse in a third acquisition. The method further includes acquiring MR signals emitted from the subject, and generating phase images based on the MR signals. The method also includes generating volumetric vector field maps based on the phase images, wherein the volumetric vector field maps include concomitant field at each spatial location in a 3D volume, the concomitant field represented as a vector. In addition, the method includes outputting the volumetric vector field maps.

    SYSTEM AND METHOD FOR OSCILLATORY EDDY CURRENT CORRECTION FOR DIFFUSION-WEIGHTED ECHO-PLANAR IMAGING
    2.
    发明公开
    SYSTEM AND METHOD FOR OSCILLATORY EDDY CURRENT CORRECTION FOR DIFFUSION-WEIGHTED ECHO-PLANAR IMAGING 审中-公开

    公开(公告)号：US20240192299A1

    公开(公告)日：2024-06-13

    申请号：US18079147

    申请日：2022-12-12

    申请人： GE Precision Healthcare LLC

    发明人： Hua Li ,  Lei Gao ,  Gaohong Wu

    IPC分类号： G01R33/565 ,  G01R33/48 ,  G01R33/563

    CPC分类号： G01R33/56518 ,  G01R33/4818 ,  G01R33/56341

    摘要： A method for correcting diffusion-weighted echo-planar imaging data (DW-EPI) includes obtaining a first reference scan with no diffusion gradients applied, a second reference scan with a diffusion gradient applied only along a frequency direction, a third reference scan with the diffusion gradient applied only along a phase direction, and a fourth reference scan with the diffusion gradient applied only along a slice direction acquired utilizing an MRI scanner, wherein the reference scans lack phase encoding. The method includes obtaining DW-EPI data acquired utilizing the MRI scanner, wherein the DW-EPI data includes phase errors due to oscillatory eddy currents causing time-varying Bo shift. The method includes generating a phase correction factor based on the reference scans and correcting the phase errors due to the oscillatory eddy currents in the DW-EPI data independent of diffusion gradient direction utilizing the phase correction factor to generate corrected DW-EPI data.

    DIXON-TYPE WATER/FAT SEPARATION MR IMAGING
    3.
    发明公开
    DIXON-TYPE WATER/FAT SEPARATION MR IMAGING 审中-公开

    公开(公告)号：US20240094320A1

    公开(公告)日：2024-03-21

    申请号：US18275816

    申请日：2022-02-08

    申请人： KONINKLIJKE PHILIPS N.V.

    发明人： Holger Eggers

    IPC分类号： G01R33/48 ,  G01R33/385 ,  G01R33/50 ,  G01R33/56 ,  G01R33/565

    CPC分类号： G01R33/4828 ,  G01R33/385 ,  G01R33/50 ,  G01R33/5608 ,  G01R33/56518

    摘要： The invention relates to a method of Dixon-type MR imaging. The object (10) is subjected to a dual- or multi-acquisition imaging sequence comprising a series of temporally equidistant RF pulses. An echo signal is generated in the presence of a readout magnetic field gradient in each time interval (TR) between successive RF pulses, with the echo time varying between at least a first value (TE1) associated with a first acquisition (ACQ1) and a second value (TE2) associated with a second acquisition (ACQ2). The invention proposes that at least one of the magnetic field gradients preceding and/or succeeding the readout magnetic field gradient in each time interval (TR) is temporally shifted, varied in duration and/or varied in amplitude between time intervals (TR). In this way, a reduction of the acoustic noise generated by the multi-acquisition Dixon sequence and, thus, of the discomfort for patients undergoing a corresponding examination is achieved. The echo signals are recorded and an MR image is reconstructed with separating signal contributions from water and fat based on the recorded echo signals of the at least two acquisitions (ACQ1, ACQ2). Moreover the invention relates to an MR device (1) and to a computer program to be run on an MR device (1).

    Magnetic resonance imaging apparatus and method of compensating for error magnetic field
    4.
    发明授权
    Magnetic resonance imaging apparatus and method of compensating for error magnetic field 有权

    公开(公告)号：US11789101B2

    公开(公告)日：2023-10-17

    申请号：US16784354

    申请日：2020-02-07

    申请人： HITACHI, LTD.

    发明人： Naoya Sakaguchi ,  Syouichi Miyawaki ,  Hirokazu Honma

    IPC分类号： G01R33/3875 ,  G01R33/54 ,  G01R33/385 ,  G01R33/565

    CPC分类号： G01R33/3875 ,  G01R33/3852 ,  G01R33/543 ,  G01R33/56518 ,  G01R33/56563

    摘要： Provided are MRI images with excellent image quality and in which the occurrence of artifacts is suppressed by effectively removing a secondary error magnetic field, generated by compensation current (additional current), of eddy current that is caused by applying a gradient magnetic field. The present invention measures and analyzes, in advance, a secondary error magnetic field generated due to the applying of compensation current and saves the results as compensation parameters (secondary compensation parameters), uses the secondary compensation parameters to calculate a correction magnetic field output to be applied to each of a gradient magnetic field coil and a correction coil, and supplies this correction magnetic field output to the gradient magnetic field coil and the correction coil to compensate for (cancel out) the secondary error magnetic field.

    METHOD FOR GENERATING A RADIAL OR SPIRAL MRT IMAGE
    9.
    发明申请
    METHOD FOR GENERATING A RADIAL OR SPIRAL MRT IMAGE 审中-公开

    公开(公告)号：US20170307711A1

    公开(公告)日：2017-10-26

    申请号：US15517282

    申请日：2015-10-07

    申请人： SIRONA DENTAL SYSTEMS GMBH

    发明人： Stefan WUNDRAK ,  Volker RASCHE

    IPC分类号： G01R33/561 ,  G01R33/565 ,  G01R33/48

    CPC分类号： G01R33/5614 ,  G01R33/4824 ,  G01R33/56518

    摘要： Disclosed herein is a method for generating an MRI image in which a radial or spiral k-chamber path with a constant angular increment Psi is used to take an MRI image, the angular increment Psi being in the angular range of between 5-55 degrees or being in the corresponding supplementary angle Psi′ and is selected according to the formula PsiN,M=pi/(N+1/(M+tau−1)). Alternatively, for an angular increment Psi which deviates from the angle increment of the optimal distribution of n radial profiles Psiopt=180°/n, the minimum scanning efficiency of the angular increment Psi for n>21 profiles is greater than 0.95, the angular increment Psi is in an angular range of 5° to less than 68.7537°, in particular between 5-55 degrees or in the corresponding supplementary angle Psi′. Compared to the arrangement of the radial or spiral profile using the golden angle of 111.24°, the angle increments calculated according to the above formula lead to lower eddy current artifacts, for example during the use of a b-SSFP-pulse sequence.