公开(公告)号：US07336145B1

公开(公告)日：2008-02-26

申请号：US11599905

申请日：2006-11-15

申请人： Adam Charles Zelinski ,  Elfar Adalsteinsson ,  Kawin Setsompop ,  Lawrence L. Waid ,  Joerg Ulrich Fontius

发明人： Adam Charles Zelinski ,  Elfar Adalsteinsson ,  Kawin Setsompop ,  Lawrence L. Waid ,  Joerg Ulrich Fontius

IPC分类号： G01V3/00

CPC分类号： G01R33/5611 ,  G01R33/288 ,  G01R33/3415 ,  G01R33/5612 ,  G01R33/5659

摘要： Waveforms for radio-frequency (RF) excitations pulses used in magnetic resonance imaging are designed according to a Least Squares QR (LSQR) algorithm or a Conjugate Gradient Least Squares (CGLS) algorithm, to solve the linear system of equations that arises in a multi-channel RF transmit arrangement. Better management of SAR and other factors is achieved with RF pulses designed according to these algorithms, compared to the conventionally employed singular value decomposition (SVD) algorithm.

摘要翻译： 用于磁共振成像的射频（RF）激发脉冲波形根据最小二乘QR（LSQR）算法或共轭梯度最小二乘法（CGLS）算法设计，以求解多重线性方程组的线性系统 通道RF发射布置。 与常规使用的奇异值分解（SVD）算法相比，根据这些算法设计的RF脉冲可以实现SAR和其他因素的更好的管理。

公开(公告)号：US08076939B2

公开(公告)日：2011-12-13

申请号：US12422017

申请日：2009-04-10

申请人： Kawin Setsompop ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence Wald

发明人： Kawin Setsompop ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence Wald

IPC分类号： G01V3/00

CPC分类号： G01R33/583 ,  G01R33/246 ,  G01R33/3415 ,  G01R33/5611

摘要： A system and method for producing an image indicative of characteristics of a radiofrequency (“RF”) coil with a magnetic resonance imaging (“MRI”) system is disclosed. The method includes acquiring MR signals while performing a pulse sequence with the MRI system and driving the RF coil at a selected transmission power. This process is repeated a plurality of times to drive the RF coil at a different transmission powers during each repetition. A plurality of images are reconstructed from the acquired MR signals and an image indicative of RF reception characteristics of the RF coil is produced from the reconstructed images. Subsequently, an image indicative of RF transmission characteristics of the RF coil is produced using the image indicative of the RF receiver response. More specifically, only one data acquisition is necessary for each RF coil element to produce the image indicative of the RF transmission characteristics for that coil element.

摘要翻译： 公开了一种用于产生表示具有磁共振成像（“MRI”）系统的射频（“RF”）线圈的特性的图像的系统和方法。 该方法包括在用MRI系统执行脉冲序列并以选定的发射功率驱动RF线圈的同时获取MR信号。 该过程重复多次以在每次重复期间以不同的发送功率驱动RF线圈。 从所获取的MR信号重建多个图像，并且从重建图像产生表示RF线圈的RF接收特性的图像。 随后，使用表示RF接收机响应的图像来产生指示RF线圈的RF传输特性的图像。 更具体地，对于每个RF线圈元件仅需要一个数据采集来产生指示该线圈元件的RF传输特性的图像。

公开(公告)号：US20130015854A1

公开(公告)日：2013-01-17

申请号：US13181868

申请日：2011-07-13

申请人： Elfar Adalsteinsson ,  Hans-Peter Fautz ,  Kawin Setsompop ,  Lawrence Wald

发明人： Elfar Adalsteinsson ,  Hans-Peter Fautz ,  Kawin Setsompop ,  Lawrence Wald

IPC分类号： G01R33/44

CPC分类号： G01R33/56563 ,  G01R33/446 ,  G01R33/5607 ,  G01R33/5612 ,  G01R33/5614

摘要： In a magnetic resonance apparatus and operating method therefor, and in a processor that is programmed to design RF pulses for operating such a magnetic resonance apparatus, the RF pulses are designed to mitigate off-resonance effects caused by inhomogeneity of the basic (B0) magnetic field in the magnetic resonance apparatus. The RF pulses of a parallel transmit array are designed with different spatial phase distributions, that deviate from a constant phase from pulse-to-pulse, with the absolute value of the difference between respective spatial phase distributions of any two successively radiated RF pulses corresponding to the off-resonance that is caused by B0-inhomogeneity during the time between the radiation of the successive pulses. Additionally, or separately, currents supplied to the shim coils can be taken into account in the design of the RF pulses as an additional degree of freedom, with the shimming of the basic magnetic field produced by the shim currents deviating from shim currents designed to ideally produce a homogenous B0 field.

摘要翻译： 在一种磁共振装置及其操作方法中，并且在被编程为设计用于操作这种磁共振装置的RF脉冲的处理器中，RF脉冲被设计成减轻由基本（B0）磁性的不均匀性引起的非共振效应 磁场。 平行发射阵列的RF脉冲被设计为具有不同的空间相位分布，其偏离了脉冲到脉冲的恒定相位，对应于任何两个相继辐射的RF脉冲的相应空间相位分布之间的差的绝对值 在连续脉冲的辐射期间由B0不均匀性引起的非共振。 此外，或者单独地，作为附加自由度，在RF脉冲的设计中可以考虑提供给垫片线圈的电流，同时由偏置电流产生的基本磁场的匀场偏离设计成理想的电流 产生均匀的B0场。

公开(公告)号：US20100066361A1

公开(公告)日：2010-03-18

申请号：US12422017

申请日：2009-04-10

申请人： Kawin Setsompop ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence Wald

发明人： Kawin Setsompop ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence Wald

IPC分类号： G01R33/48

CPC分类号： G01R33/583 ,  G01R33/246 ,  G01R33/3415 ,  G01R33/5611

摘要： A system and method for producing an image indicative of characteristics of a radiofrequency (“RF”) coil with a magnetic resonance imaging (“MRI”) system is disclosed. The method includes acquiring MR signals while performing a pulse sequence with the MRI system and driving the RF coil at a selected transmission power. This process is repeated a plurality of times to drive the RF coil at a different transmission powers during each repetition. A plurality of images are reconstructed from the acquired MR signals and an image indicative of RF reception characteristics of the RF coil is produced from the reconstructed images. Subsequently, an image indicative of RF transmission characteristics of the RF coil is produced using the image indicative of the RF receiver response. More specifically, only one data acquisition is necessary for each RF coil element to produce the image indicative of the RF transmission characteristics for that coil element.

摘要翻译： 公开了一种用于产生表示具有磁共振成像（“MRI”）系统的射频（“RF”）线圈的特性的图像的系统和方法。 该方法包括在用MRI系统执行脉冲序列并以选定的发射功率驱动RF线圈的同时获取MR信号。 该过程重复多次以在每次重复期间以不同的发送功率驱动RF线圈。 从所获取的MR信号重建多个图像，并且从重建图像产生表示RF线圈的RF接收特性的图像。 随后，使用表示RF接收机响应的图像来产生指示RF线圈的RF传输特性的图像。 更具体地，对于每个RF线圈元件仅需要一个数据采集来产生指示该线圈元件的RF传输特性的图像。

公开(公告)号：US08148985B2

公开(公告)日：2012-04-03

申请号：US12580076

申请日：2009-10-15

申请人： Adam C Zelinski ,  Kawin Setsompop ,  Elfar Adalsteinsson ,  Vivek Goyal

发明人： Adam C Zelinski ,  Kawin Setsompop ,  Elfar Adalsteinsson ,  Vivek Goyal

IPC分类号： G01V3/00

CPC分类号： G01R33/583 ,  G01R33/288 ,  G01R33/5612

摘要： A method for reducing maximum local specific absorption rate (“SAR”) in a magnetic resonance imaging (“MRI”) system is disclosed. More specifically, a plurality of candidate radio frequency (“RF”) pulses are designed and the manner in which they are applied to a subject is determined such that the maximum local SAR is substantially reduced relative to applying the candidate RF pulse that produces the lowest maximum local SAR alone. Put another way, this “time-multiplexing” of a set of RF pulses that each produce approximately the same excitation pattern yields a lower maximum local SAR than does transmitting the individual RF pulse having the lowest local SAR over many repetition times (“TRs”). A convex optimization method is utilized to determine the manner in which the RF pulses are multiplexed in time such that a substantially lower maximum local SAR is achieved.

摘要翻译： 公开了一种在磁共振成像（“MRI”）系统中降低最大局部比吸收率（“SAR”）的方法。 更具体地，设计多个候选射频（“RF”）脉冲，并且确定它们被施加到被摄体的方式，使得最大局部SAR相对于施加产生最低的候选射频脉冲而显着减小 最大的地方特区。 换句话说，每个产生大致相同的激励模式的一组RF脉冲的这种“时间复用”产生比在许多重复时间（“TR”）发送具有最低局部SAR的单个RF脉冲的最小局部SAR更低的最小局部SAR， ）。 使用凸优化方法来确定RF脉冲在时间上多路复用的方式，使得实现基本上较低的最大局部SAR。

公开(公告)号：US20100156411A1

公开(公告)日：2010-06-24

申请号：US12544714

申请日：2009-08-20

申请人： Kawin Setsompop ,  Borjan A. Gagoski ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence L. Wald

发明人： Kawin Setsompop ,  Borjan A. Gagoski ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence L. Wald

IPC分类号： G01R33/44

CPC分类号： G01R33/583 ,  G01R33/246 ,  G01R33/4833 ,  G01R33/485 ,  G01R33/543 ,  G01R33/5612 ,  G01R33/5635 ,  G01R33/56509

摘要： A method for producing a spatially and spectrally selective radiofrequency (“RF”) excitation pulse includes establishing a desired spatial RF excitation pattern and establishing a desired spectral RF excitation pattern. The method also includes estimating an RF transmission profile map indicative of the transmission characteristics of an RF coil and determining, from the desired spatial and spectral excitation patterns and the estimated RF transmission profile map, at least one magnetic field gradient waveform indicative of locations in k-space to which RF energy is to be deposited. The method further includes determining, from the established spatial and spectral excitation patterns, the estimated RF transmission profile map, and the determined at least one gradient waveform, at least one RF excitation pulse waveform that will produce the desired spatial and spectral excitation patterns.

摘要翻译： 用于产生空间和频谱选择性射频（“RF”）激励脉冲的方法包括建立期望的空间RF激励模式并建立期望的频谱RF激励模式。 该方法还包括估计指示RF线圈的传输特性的RF传输分布图，并根据期望的空间和频谱激励模式以及估计的RF传输分布图确定表示k中的位置的至少一个磁场梯度波形 - 空间，RF能量将被放置到该空间。 该方法还包括根据建立的空间和频谱激励模式，确定估计的RF传输概况图和所确定的至少一个梯度波形，至少一个RF激励脉冲波形，其将产生期望的空间和频谱激励模式。

公开(公告)号：US20100134105A1

公开(公告)日：2010-06-03

申请号：US12580076

申请日：2009-10-15

申请人： Adam C. Zelinski ,  Kawin Setsompop ,  Elfar Adalsteinsson ,  Vivek Goyal

发明人： Adam C. Zelinski ,  Kawin Setsompop ,  Elfar Adalsteinsson ,  Vivek Goyal

IPC分类号： G01R33/48

CPC分类号： G01R33/583 ,  G01R33/288 ,  G01R33/5612

摘要： A method for reducing maximum local specific absorption rate (“SAR”) in a magnetic resonance imaging (“MRI”) system is disclosed. More specifically, a plurality of candidate radio frequency (“RF”) pulses are designed and the manner in which they are applied to a subject is determined such that the maximum local SAR is substantially reduced relative to applying the candidate RF pulse that produces the lowest maximum local SAR alone. Put another way, this “time-multiplexing” of a set of RF pulses that each produce approximately the same excitation pattern yields a lower maximum local SAR than does transmitting the individual RF pulse having the lowest local SAR over many repetition times (“TRs”). A convex optimization method is utilized to determine the manner in which the RF pulses are multiplexed in time such that a substantially lower maximum local SAR is achieved.

摘要翻译： 公开了一种在磁共振成像（“MRI”）系统中降低最大局部比吸收率（“SAR”）的方法。 更具体地，设计多个候选射频（“RF”）脉冲，并且确定它们被施加到被摄体的方式，使得最大局部SAR相对于施加产生最低的候选射频脉冲而显着减小 最大的地方特区。 换句话说，每个产生大致相同的激励模式的一组RF脉冲的这种“时间复用”产生比在许多重复时间（“TR”）发送具有最低局部SAR的单个RF脉冲的最小局部SAR更低的最小局部SAR， ）。 使用凸优化方法来确定RF脉冲在时间上多路复用的方式，使得实现基本上较低的最大局部SAR。

公开(公告)号：US08866478B2

公开(公告)日：2014-10-21

申请号：US13181868

申请日：2011-07-13

申请人： Elfar Adalsteinsson ,  Hans-Peter Fautz ,  Kawin Setsompop ,  Lawrence Wald

发明人： Elfar Adalsteinsson ,  Hans-Peter Fautz ,  Kawin Setsompop ,  Lawrence Wald

IPC分类号： G01V3/00 ,  G01R33/565 ,  G01R33/561 ,  G01R33/56 ,  G01R33/44

CPC分类号： G01R33/56563 ,  G01R33/446 ,  G01R33/5607 ,  G01R33/5612 ,  G01R33/5614

摘要： In a magnetic resonance apparatus and operating method therefor, and in a processor that is programmed to design RF pulses for operating such a magnetic resonance apparatus, the RF pulses are designed to mitigate off-resonance effects caused by inhomogeneity of the basic (B0) magnetic field in the magnetic resonance apparatus. The RF pulses of a parallel transmit array are designed with different spatial phase distributions, that deviate from a constant phase from pulse-to-pulse, with the absolute value of the difference between respective spatial phase distributions of any two successively radiated RF pulses corresponding to the off-resonance that is caused by B0-inhomogeneity during the time between the radiation of the successive pulses. Additionally, or separately, currents supplied to the shim coils can be taken into account in the design of the RF pulses as an additional degree of freedom, with the shimming of the basic magnetic field produced by the shim currents deviating from shim currents designed to ideally produce a homogenous B0 field.

摘要翻译： 在一种磁共振装置及其操作方法中，并且在被编程为设计用于操作这种磁共振装置的RF脉冲的处理器中，RF脉冲被设计成减轻由基本（B0）磁性的不均匀性引起的非共振效应 磁场。 平行发射阵列的RF脉冲被设计为具有不同的空间相位分布，其偏离了脉冲到脉冲的恒定相位，对应于任何两个相继辐射的RF脉冲的相应空间相位分布之间的差的绝对值 在连续脉冲的辐射期间由B0不均匀性引起的非共振。 此外，或者单独地，作为附加自由度，在RF脉冲的设计中可以考虑提供给垫片线圈的电流，同时由偏置电流产生的基本磁场的匀场偏离设计成理想的电流 产生均匀的B0场。

公开(公告)号：US08085044B2

公开(公告)日：2011-12-27

申请号：US12544714

申请日：2009-08-20

申请人： Kawin Setsompop ,  Borjan A. Gagoski ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence L Wald

发明人： Kawin Setsompop ,  Borjan A. Gagoski ,  Elfar Adalsteinsson ,  Vijayanand Alagappan ,  Lawrence L Wald

IPC分类号： G01V3/00

CPC分类号： G01R33/583 ,  G01R33/246 ,  G01R33/4833 ,  G01R33/485 ,  G01R33/543 ,  G01R33/5612 ,  G01R33/5635 ,  G01R33/56509

摘要： A method for producing a spatially and spectrally selective radiofrequency (“RF”) excitation pulse includes establishing a desired spatial RF excitation pattern and establishing a desired spectral RF excitation pattern. The method also includes estimating an RF transmission profile map indicative of the transmission characteristics of an RF coil and determining, from the desired spatial and spectral excitation patterns and the estimated RF transmission profile map, at least one magnetic field gradient waveform indicative of locations in k-space to which RF energy is to be deposited. The method further includes determining, from the established spatial and spectral excitation patterns, the estimated RF transmission profile map, and the determined at least one gradient waveform, at least one RF excitation pulse waveform that will produce the desired spatial and spectral excitation patterns.

摘要翻译： 用于产生空间和频谱选择性射频（“RF”）激励脉冲的方法包括建立期望的空间RF激励模式并建立期望的频谱RF激励模式。 该方法还包括估计指示RF线圈的传输特性的RF传输分布图，并根据期望的空间和频谱激励模式以及估计的RF传输分布图确定表示k中的位置的至少一个磁场梯度波形 - 空间，RF能量将被放置到该空间。 该方法还包括根据建立的空间和频谱激励模式，确定估计的RF传输概况图和所确定的至少一个梯度波形，至少一个RF激励脉冲波形，其将产生期望的空间和频谱激励模式。

公开(公告)号：US20120256626A1

公开(公告)日：2012-10-11

申请号：US13083342

申请日：2011-04-08

申请人： Elfar Adalsteinsson ,  Joonsung Lee ,  Lawrence L. Wald ,  Matthias L. Gebhardt

发明人： Elfar Adalsteinsson ,  Joonsung Lee ,  Lawrence L. Wald ,  Matthias L. Gebhardt

IPC分类号： G01R33/48 ,  G01R33/44

CPC分类号： G01R33/5612 ,  G01R33/288

摘要： A method of designing a parallel transmission radio frequency (RF) pulse for a magnetic resonance imaging (MRI) system includes compressing a model for a subject to be scanned by the MRI system into a plurality of voxel clusters, each voxel cluster defining a virtual observation point with a peak sensitivity to local specific absorption rate (SAR) for the voxel cluster, and defining the parallel transmission RF pulse based on an approximation of a minimization criterion having a local SAR component based on the peak sensitivity of each virtual observation point, the approximation comprising a weighted sum of the local SAR values for each virtual observation point.

摘要翻译： 设计用于磁共振成像（MRI）系统的并行传输射频（RF）脉冲的方法包括将由MRI系统扫描的对象的模型压缩成多个体素簇，每个体素簇定义虚拟观察 点对于体素簇具有对局部比吸收率（SAR）的峰值灵敏度，并且基于基于每个虚拟观测点的峰值灵敏度的具有局部SAR分量的最小化准则的近似来定义并行发射RF脉冲， 近似值包括每个虚拟观测点的局部SAR值的加权和。