公开(公告)号：US5027071A

公开(公告)日：1991-06-25

申请号：US489124

申请日：1990-03-05

申请人： Christopher J. Hardy ,  Peter B. Roemer ,  Otward M. Mueller

发明人： Christopher J. Hardy ,  Peter B. Roemer ,  Otward M. Mueller

IPC分类号： A61B5/055 ,  G01R33/32 ,  G01R33/36 ,  G01R33/385 ,  G01R33/387 ,  G01R33/54 ,  G01R33/565 ,  G06T1/00

CPC分类号： G01R33/385 ,  G01R33/56518 ,  G01R33/3607 ,  G01R33/3852

摘要： A method of reducing slice profile degradation due to gradient signal amplitude ripple, has steps of: sensing the gradient signal ripple amplitude; normalizing the sensed ripple signal amplitude responsive to the gradient amplitude commanded; and modulating the RF signal amplitude with the adjusted-amplitude ripple signal, to cause the RF and gradient magnetic fields to have an effective vector pointing substantially in the same direction, during the slice-selection interval, as would the effective field vector formed with a gradient field devoid of ripple. Apparatus for reducing the slice profile degradation modulates the RF signal with the ripple envelope obtained from the output of the gradient signal amplifier, by a signal controlled by the gradient amplifier input.

公开(公告)号：US4961054A

公开(公告)日：1990-10-02

申请号：US376074

申请日：1989-07-06

申请人： John N. Park ,  Otward M. Mueller ,  Peter B. Roemer

发明人： John N. Park ,  Otward M. Mueller ,  Peter B. Roemer

IPC分类号： G01R33/20 ,  A61B5/055 ,  G01R33/38 ,  G01R33/385 ,  G01R33/48 ,  H03K17/567

CPC分类号： G01R33/3852 ,  H03K17/567

摘要： A gradient current speed-up circuit, for use in a higher-speed NMR imaging system with a gradient power amplifier and an associated gradient coil, has an energy-storage element, with an inductance typically between 5 and 20 times the inductance of the associated gradient coil. A plurality of semiconductor switching elements receive the current output of the energy-storage element; and the associated gradient coil is connected between selected ones of these semiconductors devices. The semiconductor devices are turned on and off in selected patterns, to cause the energy-storage element current to be suddenly applied to and removed from flow through the associated gradient coil.

公开(公告)号：US4926125A

公开(公告)日：1990-05-15

申请号：US234729

申请日：1988-08-22

申请人： Peter B. Roemer

发明人： Peter B. Roemer

IPC分类号： G01R33/20 ,  A61B5/055 ,  G01R33/38 ,  G01R33/385 ,  G01R33/422 ,  G01R33/48

CPC分类号： G01R33/422 ,  G01R33/385

摘要： A novel surface gradient assembly for high-speed, high-resolution NMR imaging has at least one substantially planar gradient coil. Each of the planar coils is disposed substantially parallel to any other planar coil of the assembly, and in a chosen plane of two selected Cartesian coordinates. Thus, one or more, planar coils lying in, say, the XZ plane can provide a magnetic gradient field in 1, 2 or all 3 of the X, Y and/or Z directions. Each coil can be formed of 1, 2, 4 or more windings, each of which is a "fingerprint" coil of configuration established by current-flow stream functions. An RF shield can be placed between the substantially planar gradient coil(s) and a RF antenna, to prevent interaction between the antenna and gradient coils, so that the quality factor (Q) of the RF antenna is not appreciable lowered.

公开(公告)号：US4887039A

公开(公告)日：1989-12-12

申请号：US288668

申请日：1988-12-22

申请人： Peter B. Roemer ,  William A. Edelstein ,  Cecil E. Hayes ,  Matthew G. Eash

发明人： Peter B. Roemer ,  William A. Edelstein ,  Cecil E. Hayes ,  Matthew G. Eash

IPC分类号： H01Q1/50 ,  A61B5/055 ,  G01R33/34 ,  G01R33/36

CPC分类号： G01R33/34046 ,  G01R33/3628

摘要： A method for providing plural coaxial cable connections, each to a different portion of a single radio-frequency (RF) antenna without requiring the use of isolation means at any RF connection, determines at least a point within the antenna having a desired common potential adjacent to each of the different portions to which one of the coaxial cable connections is to be made; Then forms a separate segment of each different portion which is located substantially at the common potential and is reactively separated from adjacent segments of the associated portion; and connects a shield conductor of an associated coaxial cable to the separate segment, while connecting a center conductor of that same associated coaxial cable to a selected one of the adjacent segments of that different portion.

公开(公告)号：US4871969A

公开(公告)日：1989-10-03

申请号：US288605

申请日：1988-12-22

申请人： Peter B. Roemer ,  William A. Edelstein

发明人： Peter B. Roemer ,  William A. Edelstein

IPC分类号： G01R33/385 ,  G01R33/422

CPC分类号： G01R33/422 ,  G01R33/385

摘要： An RF shield, for use between a set of gradient coils and an RF coil, is hollow formed of a single conductor sheet divided into first and second opposed halves, each having a set of conductive streamline portions with a series of nonconductive cut lines formed therebetween. Each of the cut lines is parallel to the RF current and is of a generally oval shape. Each of the shield conductor loops is further separated into a "C"-shaped conductive portion, along at least one radial line, and the C portions are then connected so as to continue shielding the RF current, yet pass gradient magnetic fields in all three mutually orthogonal directions of a Cartesian coordinate system.

摘要翻译： 在一组梯度线圈和RF线圈之间使用的RF屏蔽件由分成第一和第二相对半部的单个导体片形成，其中每个具有一组导电流线部分，其间形成有一系列不导电的切割线 。 每个切割线平行于RF电流并且具有大致椭圆形的形状。 每个屏蔽导体环路沿着至少一个径向线进一步分成“C”形导电部分，然后将C部分连接，以便继续屏蔽RF电流，然后在所有三个方向通过梯度磁场 笛卡尔坐标系的相互正交方向。