公开(公告)号：US5436600A

公开(公告)日：1995-07-25

申请号：US283050

申请日：1994-07-29

申请人： John Van Heteren ,  Mitsuaki Arakawa ,  Lawrence E. Crooks ,  John C. Hoenninger, III ,  Thomas McDermott ,  Keiji Furui

发明人： John Van Heteren ,  Mitsuaki Arakawa ,  Lawrence E. Crooks ,  John C. Hoenninger, III ,  Thomas McDermott ,  Keiji Furui

IPC分类号： G01R33/36 ,  G01R33/48 ,  H03B21/02 ,  H03B28/00 ,  G01R33/24 ,  H03C1/52 ,  H03C1/60

CPC分类号： H03B21/02 ,  G01R33/3607 ,  G01R33/446 ,  H03B28/00

摘要： A local frequency generator employing a single crystal oscillator, latches and direct digital synthesizer circuits digitally produces all signals needed in the transmitter channel of a MRI system to generate MRI transmitter RF pulses. The local frequency generator is operable in both the single side band and double side band modes and has the capability of switching between the modes. The generator is constructed with a phase resetting capability for providing the plural output frequencies needed for making plural MRI slices.

摘要翻译： 使用单晶振荡器的本地频率发生器，锁存器和直接数字合成器电路数字地产生MRI系统的发射器通道中所需的所有信号，以产生MRI发射器RF脉冲。 本地频率发生器可以在单边带和双边带模式下工作，并具有在各种模式之间切换的能力。 该发生器具有相位复位功能，用于提供制作多个MRI切片所需的多个输出频率。

公开(公告)号：US4318043A

公开(公告)日：1982-03-02

申请号：US120875

申请日：1980-02-12

申请人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

发明人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

IPC分类号： G01R33/54 ,  G01N27/00

CPC分类号： G01R33/54

摘要： Densities of resonant nuclei within elemental volumes along a line are measured using the nuclear magnetic resonance phenomenon called "spin echo". A first planar volume of nuclei is selectively excited to nutate spins by approximately 90.degree.. Thereafter a second planar volume of nuclei, transverse to the first planar volume, is selectively excited to nutate spins by approximately 180.degree.. The nuclei in the line volume common to both of the planar volumes thereafter generate characteristic spin echo signals. A magnetic gradient is established along this line volume during the spin echo read out so that the resultant spin echo signals can be processed to determine the respective densities of resonant nuclei along the line volume. Appropriate phasing of the excitations enables interference with the spin echo signals by the free induction decay to be eliminated. To enable rapid development, successive line volumes are read out which do not lie in previously excited planes.

摘要翻译： 使用称为“自旋回波”的核磁共振现象来测量沿着线的元素体积内的谐振核的密度。 选择性地激发第一平面体积的核，使其旋转约90度。 此后，横向于第一平面体积的第二平面体积的核被选择性地激发，使自旋旋转约180度。 两个平面体积共同的线体积中的原子核之后产生特征自旋回波信号。 在自旋回波读出期间，沿该线体积建立磁梯度，使得可以处理所得到的自旋回波信号以确定沿线体积的共振核的相应密度。 兴奋的适当定相可以通过自由感应衰减来消除自旋回波信号的干扰。 为了实现快速发展，读出了不在以前激发的平面内的连续线体积。

公开(公告)号：US4297637A

公开(公告)日：1981-10-27

申请号：US926571

申请日：1978-07-20

申请人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

发明人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

IPC分类号： A61B10/00 ,  A61B5/055 ,  G01R33/48 ,  G01R33/50 ,  G01N27/00

CPC分类号： G01R33/50

摘要： Densities of resonant nuclei within elemental volumes along a line are measured using the nuclear magnetic resonance phenomenon called "spin echo." A first planar volume of nuclei is selectively excited to nutate spins by approximately 90.degree.. Thereafter a second planar volume of nuclei, transverse to the first planar volume, is selectively excited to nutate spins by approximately 180.degree.. The nuclei in the line volume common to both of the planar volumes thereafter generate characteristic spin echo signals. A magnetic gradient is established along this line volume during the spin echo read out so that the resultant spin echo signals can be processed to determine the respective densities of resonant nuclei along the line volume. Special pulsing sequences for rapidly effecting measurement of successive multiple line volumes and suitable apparatus for effecting such sequences are also described.

摘要翻译： 使用称为“自旋回波”的核磁共振现象测量沿着线的元素体积内的谐振核的密度。 选择性地激发第一平面体积的核，使其旋转约90度。 此后，横向于第一平面体积的第二平面体积的核被选择性地激发，使自旋旋转约180度。 两个平面体积共同的线体积中的原子核之后产生特征自旋回波信号。 在自旋回波读出期间，沿该线体积建立磁梯度，使得可以处理所得到的自旋回波信号以确定沿线体积的共振核的相应密度。 还描述了用于快速实现连续多线体积的测量的特殊脉冲序列和用于实现这种序列的合适装置。

公开(公告)号：US4599565A

公开(公告)日：1986-07-08

申请号：US515117

申请日：1983-07-19

申请人： John C. Hoenninger, III ,  Lawrence E. Crooks ,  Mitsuaki Arakawa ,  Jerome R. Singer

发明人： John C. Hoenninger, III ,  Lawrence E. Crooks ,  Mitsuaki Arakawa ,  Jerome R. Singer

IPC分类号： A61B10/00 ,  A61B5/055 ,  G01N24/08 ,  G01R33/48 ,  G01R33/54 ,  G01R33/561 ,  G01R33/567 ,  G01N27/00

CPC分类号： G01R33/4835 ,  G01N24/08 ,  G01R33/561 ,  G01R33/4824

摘要： An imaging NMR scanner generates multi-dimensional NMR spin echo responses from selected sub-volumes of an object. 90.degree. and 180.degree. r.f. nutation pulses are used together with a variable amplitude gradient between these nutation pulses to phase encode a second dimension in the spin echo response which is already phase-encoded in a first dimension by use of a magnetic gradient during signal readout. Two-dimensional Fourier transforms or multiple angle projection reconstruction processes are then used to generate an array of pixel value data signals representing a visual image of the point-by-point spatial distribution of nutated nuclei within the object. Image artifacts potentially caused by relatively moving elements of the object are avoided by selecting the spin echo generating sub-volumes to avoid the moving elements. High resolution images of sub-volumes of interest can be obtained by selection of a sub-volume of interest in conjunction with these reconstruction techniques. Solutions for possible aliasing artifacts are also presented as are three-dimensional reconstruction techniques using NMR spin echo responses from such selected sub-volumes.

摘要翻译： 成像NMR扫描仪从对象的选定子体积产生多维NMR自旋回波响应。 90°和180°r.f。 章动脉冲与这些章动脉冲之间的可变幅度梯度一起使用，以通过在信号读出期间使用磁梯度在第一维度上对自旋回波响应中的第二维进行相位编码。 然后使用二维傅里叶变换或多角度投影重建处理来生成表示对象内的章动核的逐点空间分布的视觉图像的像素值数据信号的阵列。 通过选择自旋回波生成子体积以避免移动的元素来避免可能由对象的相对移动元素引起的图像伪像。 可以通过结合这些重建技术选择感兴趣的子体积来获得感兴趣的子体积的高分辨率图像。 还可以用三维重建技术来呈现可能的混叠伪影的解决方案，这些技术使用来自这些选定子体积的NMR自旋回波响应。

公开(公告)号：USRE33259E

公开(公告)日：1990-07-10

申请号：US191025

申请日：1988-05-06

申请人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa ,  Jerome R. Singer

发明人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa ,  Jerome R. Singer

IPC分类号： G01R33/50

CPC分类号： G01R33/50

摘要： An imaging NMR scanner obtains plural spin echo signals during each of successive measurement cycles permitting determination of the T2 parameter for each display pixel after but a single measurement sequence. The amplitude of the NMR spin echo responses is dependent on an "a" machine parameter (the elapsed time between initiation of a given measurement cycle and the occurrence of the NMR response) and upon a "b" machine parameter (the elapsed time between initiation of successive measurement cycles). These a and b machine time parameters are selectively controlled to enhance resultant image contrast between different types of tissue or other internal structures of an object under examination. Special phase control circuits ensure the repeatability of relative phasing between successive NMR responses from the same measured volume and/or of reference RF signals utilized to frequency translate and synchronously demodulate the NMR responses in the successive measurement cycles of a complete measurement sequence. Special sub-sequences of four measurement cycles are utilized to provide resultant combined spin echo measurements substantially independent of FID signal components.

公开(公告)号：US4471305A

公开(公告)日：1984-09-11

申请号：US331008

申请日：1981-12-15

申请人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

发明人： Lawrence E. Crooks ,  John C. Hoenninger, III ,  Mitsuaki Arakawa

IPC分类号： G01N24/08 ,  G01R33/50 ,  G01R33/56 ,  G01R33/08

CPC分类号： G01N24/08 ,  G01R33/50 ,  G01R33/56 ,  Y10S505/844

摘要： An imaging NMR scanner obtains plural spin echo signals during each of successive measurement cycles permitting determination of the T2 parameter for each display pixel after but a single measurement sequence. The amplitude of the NMR spin echo responses is dependent on an "a" machine parameter (the elapsed time between initiation of a given measurement cycle and the occurrence of the NMR response) and upon a "b" machine parameter (the elapsed time between initiation of successive measurement cycles). These a and b machine time parameters are selectively controlled to enhance resultant image contrast between different types of tissue or other internal structures of an object under examination. Special phase control circuits ensure the repeatability of relative phasing between successive NMR responses from the same measured volume and/or of reference RF signals utilized to frequency translate and synchronously demodulate the NMR responses in the successive measurement cycles of a complete measurement sequence. Special sub-sequences of four measurement cycles are utilized to provide resultant combined spin echo measurements substantially independent of FID signal components.

摘要翻译： 成像NMR扫描仪在每个连续测量循环期间获得多个自旋回波信号，允许在单个测量序列之后确定每个显示像素的T2参数。 NMR自旋回波响应的幅度取决于“a”机器参数（给定测量周期的启动和NMR响应的发生之间的经过时间）和“b”机器参数（启动之间的经过时间） 的连续测量循环）。 选择性地控制这些a和b机器时间参数以增强被检查物体的不同类型的组织或其他内部结构之间的合成图像对比度。 特殊相位控制电路确保相同测量体积和/或参考RF信号的连续NMR响应之间的相对相位的重复性，用于在完整测量序列的连续测量循环中频率平移和同步解调NMR响应。 利用四个测量周期的特殊子序列来提供基本上独立于FID信号分量的合成自旋回波测量结果。

公开(公告)号：US5461314A

公开(公告)日：1995-10-24

申请号：US139177

申请日：1993-10-21

申请人： Mitsuaki Arakawa ,  Hsu Chang ,  John Van Heteren

发明人： Mitsuaki Arakawa ,  Hsu Chang ,  John Van Heteren

IPC分类号： A61B5/055 ,  G01R33/341 ,  G01R33/3415 ,  G01R33/36 ,  G01R33/58 ,  G01V3/00

CPC分类号： G01R33/3628 ,  G01R33/3415 ,  G01R33/3642 ,  G01R33/3678 ,  G01R33/583

摘要： A front end unit (32) for a magnetic resonance imaging (MRI) system (20) comprises a plurality of coil attachment ports (46) to which an RF signal or tuning signal is selectively routed thereby permitting, during operation, coils (22) to remain attached to each of the plurality of ports. A signal routing controller (28, 30) selects to which of the ports the RF signal or tuning signal is to be routed. The RF front end Knit (32) is also known as the relay switchboard assembly or RSB. Each port of the RF front end is attached to a different RF coil or RF coil combination. Tuning and imaging operations can be conducted for a plurality of coils in succession, without coils having to be detached from the RF front end. The signal routing controller selectively applies the RF signal (from an RF unit) or the tuning signal (from a tuning controller) to the selected coil through a signal path unique to the selected coil. Coils not selected to be operative can be detuned.

摘要翻译： 用于磁共振成像（MRI）系统（20）的前端单元（32）包括多个线圈附接端口（46），RF信号或调谐信号被选择性地布线到所述多个线圈附接端口，从而在操作期间允许线圈（22） 以保持附接到多个端口中的每一个。 信号路由选择控制器（28,30）选择RF信号或调谐信号要路由的哪个端口。 RF前端针织（32）也称为中继配电板组件或RSB。 RF前端的每个端口连接到不同的RF线圈或RF线圈组合。 可以连续地对多个线圈进行调谐和成像操作，而不必将线圈从RF前端分离。 信号路由控制器通过所选线圈唯一的信号路径选择性地将RF信号（来自RF单元）或调谐信号（来自调谐控制器）施加到所选择的线圈。 不选择操作的线圈可能失谐。

公开(公告)号：US5565779A

公开(公告)日：1996-10-15

申请号：US476586

申请日：1995-06-07

申请人： Mitsuaki Arakawa ,  Hsu Chang ,  John Van Heteren

发明人： Mitsuaki Arakawa ,  Hsu Chang ,  John Van Heteren

IPC分类号： A61B5/055 ,  G01R33/341 ,  G01R33/3415 ,  G01R33/36 ,  G01R33/58 ,  G01V3/00

CPC分类号： G01R33/3628 ,  G01R33/3415 ,  G01R33/3642 ,  G01R33/3678 ,  G01R33/583

摘要： A front end unit (32) for a magnetic resonance imaging (MRI) system (20) comprises a plurality of coil attachment ports (46) to which an RF signal or tuning signal is selectively routed thereby permitting, during operation, coils (22) to remain attached to each of the plurality of ports. A signal routing controller (28, 30) selects to which of the ports the RF signal or tuning signal is to be routed. The RF front end unit (32) is also known as the relay switch board assembly or RSB. Each port of the RF front end is attached to a different RF coil or RF coil combination. Tuning and imaging operations can be conducted for a plurality of coils in succession, without coils having to be detached from the RF front end. The signal routing controller selectively applies the RF signal (from an RF unit) or the tuning signal (from a tuning controller) to the selected coil through a signal path unique to the selected coil. Coils not selected to be operative can be detuned.

摘要翻译： 用于磁共振成像（MRI）系统（20）的前端单元（32）包括多个线圈附接端口（46），RF信号或调谐信号被选择性地布线到所述多个线圈附接端口，从而在操作期间允许线圈（22） 以保持附接到多个端口中的每一个。 信号路由选择控制器（28,30）选择RF信号或调谐信号要路由的哪个端口。 RF前端单元（32）也称为继电器开关板组件或RSB。 RF前端的每个端口连接到不同的RF线圈或RF线圈组合。 可以连续地对多个线圈进行调谐和成像操作，而不必将线圈从RF前端分离。 信号路由控制器通过所选线圈唯一的信号路径选择性地将RF信号（来自RF单元）或调谐信号（来自调谐控制器）施加到所选择的线圈。 不选择操作的线圈可能失谐。

公开(公告)号：US5483158A

公开(公告)日：1996-01-09

申请号：US139178

申请日：1993-10-21

申请人： John van Heteren ,  Mitsuaki Arakawa

发明人： John van Heteren ,  Mitsuaki Arakawa

IPC分类号： A61B5/055 ,  G01R33/3415 ,  G01R33/36 ,  G01R33/58 ,  G01R33/28

CPC分类号： G01R33/3628 ,  G01R33/3415 ,  G01R33/583

摘要： An RF front end unit (32) for a magnetic resonance imaging (MRI) system (20) has transmit and receive channels to which a plurality of coils (22) can remain attached during operation (including RF coils having differing types of matching circuits), and facilitates switching between a plurality of attached coils. Methods and apparatus are additionally provided for selectively tuning differing RF coils, including both high power coils (22B, 22C) and varactor-tuned coils (22D). The tuning of a high power coil involves using a remote impedance match tuning network (RTU) (26) for a coarse tuning operation and, if necessary, a fine tuning operation. In performing the coarse tuning operation separately for In-Phase ("I") and Quadrature ("Q") channels, a tuning controller (60) determines the effective load impedance of each of the RF coil channels by quadrature demodulation of their reflected signals. The tuning controller (60) then evaluates a computerized model of the impedance match tuning network in order to determine and set coarse values for the adjustable impedances of the RTU. In tuning varactor coils, the tuning controller chooses a starting point for the varactor coil tune and then executes a two-dimensional bisection search operation to locate a candidate for the tuned point. The bisection search is followed by a starburst operation for examining the magnitude of reflected signals at points in a starburst or asterisk pattern about the candidate point.

摘要翻译： 用于磁共振成像（MRI）系统（20）的RF前端单元（32）具有在操作期间多个线圈（22）可以保持附接的发射和接收通道（包括具有不同类型的匹配电路的RF线圈） 并且便于在多个附接线圈之间切换。 还提供了用于选择性地调谐包括高功率线圈（22B，22C）和变容二极管调谐线圈（22D）的不同RF线圈的方法和装置。 大功率线圈的调谐涉及使用远程阻抗匹配调谐网络（RTU）（26）进行粗调操作，如果需要，可进行微调操作。 在对同相（“I”）和正交（“Q”）通道分别执行粗调操作时，调谐控制器（60）通过它们的反射信号的正交解调来确定每个RF线圈通道的有效负载阻抗 。 调谐控制器（60）然后评估阻抗匹配调谐网络的计算机化模型，以便确定并设置RTU的可调节阻抗的粗略值。 在调谐变容二极管线圈时，调谐控制器选择变容二极管线圈调谐的起始点，然后执行二维平分搜索操作以定位调谐点的候选。 平分搜索之后是星爆操作，用于检查关于候选点的星爆或星号图案中的点处的反射信号的大小。

公开(公告)号：US4783629A

公开(公告)日：1988-11-08

申请号：US105737

申请日：1987-10-07

申请人： Mitsuaki Arakawa ,  Lawrence E. Crooks

发明人： Mitsuaki Arakawa ,  Lawrence E. Crooks

IPC分类号： G01R33/36 ,  G01R33/20

CPC分类号： G01R33/3628 ,  G01R33/34069

摘要： An RF coil for a magnetic resonance imaging device using nuclear magnetic resonance phenomena includes self-tracking ganged coupling capacitors which provide impedance matching and also tune out coil inductance to establish resonance at the RF operating frequency. At least one variable capacitor connected in parallel with the RF coil is mechanically ganged to at least one variable capacitor connected in series to the RF coil. The parallel and series capacitances are initially set to achieve resonance at a desired operating frequency. As the shaft of one variable capacitor is rotated in a first direction through a given angle, the shaft of the other variable capacitor rotates in the opposite direction through the same angle, thereby varying the ratio (but not the sum) of parallel and series capacitances. A servo controller connected to a standing wave ratio detector automatically adjusts the ratio of parallel to series capacitances to optimize impedance matching between the source and the RF coil.

摘要翻译： 用于使用核磁共振现象的磁共振成像装置的RF线圈包括提供阻抗匹配的自跟踪组合耦合电容器，并且还调出线圈电感以在RF操作频率处建立谐振。 与RF线圈并联连接的至少一个可变电容器被机械地组合到与RF线圈串联连接的至少一个可变电容器。 初始设置并联和串联电容以在期望的工作频率下实现谐振。 当一个可变电容器的轴沿第一方向旋转一定角度时，另一个可变电容器的轴沿相反的方向旋转相同的角度，从而改变并联和串联电容的比值（而不是总和） 。 连接到驻波比检测器的伺服控制器自动调节并联到串联电容的比率，以优化源极和RF线圈之间的阻抗匹配。