公开(公告)号：US07538548B2

公开(公告)日：2009-05-26

申请号：US11420224

申请日：2006-05-25

申请人： Hector E. Avram ,  James D. Hale ,  Ilya Simovsky ,  David M. Kramer

发明人： Hector E. Avram ,  James D. Hale ,  Ilya Simovsky ,  David M. Kramer

IPC分类号： G01V3/00

CPC分类号： G01R33/56341 ,  G01R33/5608 ,  G01R33/5615 ,  G01R33/5617 ,  G01R33/565 ,  G01R33/56509

摘要： In preferred embodiments, a fast spin echo imaging technique is provided that is insensitive to violations of the Carr Purcell Meiboom Gill (CPMG) condition. Diffusion gradients disrupt the CPMG condition, and, hence, the present fast spin echo method is compatible with diffusion measurements and diffusion weighted imaging. The preferred embodiments of the present technique involve splitting of spin echoes into echo pairs. Spin echoes are split by adjustment (in magnitude or duration) of an initial readout gradient pulse. A train of echo pairs is captured. A first image is constructed using the first echoes of each pair. Also, a second image is constructed using the second echoes of each pair. Hybrid radial Cartesian methods are used for constructing the first and second images. The first and second images are constructed independently of one another. Independent image construction renders the method insensitive to violation of the CPMG condition. Finally, the two images are combined to form a final image.

摘要翻译： 在优选实施例中，提供了对违反Carr Purcell Meiboom Gill（CPMG）条件不敏感的快速自旋回波成像技术。 扩散梯度破坏CPMG条件，因此，本发明的快速自旋回波方法与扩散测量和扩散加权成像兼容。 本技术的优选实施例涉及将自旋回波分解为回波对。 旋转回波通过初始读数梯度脉冲的调整（幅度或持续时间）分割。 一串回波对被捕获。 使用每对的第一个回波构建第一个图像。 此外，使用每对的第二回波来构建第二图像。 混合径向笛卡尔方法用于构建第一和第二图像。 第一和第二图像彼此独立构建。 独立的图像构造使得方法对违反CPMG条件不敏感。 最后，将两张图像合并形成最终图像。

公开(公告)号：US5157330A

公开(公告)日：1992-10-20

申请号：US659181

申请日：1991-02-22

申请人： Leon Kaufman ,  Joseph W. Carlson ,  David M. Kramer ,  James D. Hale ,  Kingman Yee

发明人： Leon Kaufman ,  Joseph W. Carlson ,  David M. Kramer ,  James D. Hale ,  Kingman Yee

IPC分类号： G01R33/565

CPC分类号： G01R33/56563

摘要： A measure of magnetic field inhomogeneity along a phase-encoded (e.g. y-axis) dimension is derived in k-space from previously acquired MRI phase-encoded projection data. From this, a measure of MRI data skewing caused by such inhomogeneity is obtained and used to compensate therefor. Since the MRI data is to be multi-dimensionally Fourier Transformed in most instances anyway, a transform in the relevant phase encoded dimension (e.g., y-axis) is taken followed with phase shifting each digitized data point by an amount proportional to the measured magnitude of inhomogeneity and to the datum coordinate in the read-out dimension (e.g., x-axis) and to the datum coordinate in each phase-encode dimension (e.g., y-axis) before the data is further Fourier Transformed with respect to the read-out dimension (e.g., x-axis). If two-dimensional phase encoding is employed (e.g., as in 3DFT), then a second level of similar inhomogeneity compensation can be had in the third dimension (e.g., z-axis) as well.

摘要翻译： 在先前获得的MRI相位编码投影数据中，在k空间中导出沿着相位编码（例如y轴）尺寸的磁场不均匀性的度量。 由此可以获得由这种不均匀性引起的MRI数据偏移的量度，并用于补偿。 由于MRI数据在大多数情况下要进行多维傅立叶变换，所以在相关的相位编码维度（例如，y轴）中进行变换，然后将每个数字化数据点的相移量与测量的幅度成正比 在数据进一步相对于读取的傅里叶变换之前，在读出维度（例如，x轴）和每个相位编码维度（例如，y轴）中的基准坐标之间的基准坐标 - 尺寸（例如，x轴）。 如果采用二维相位编码（例如，如3DFT中那样），则在第三维度（例如，z轴）中可以具有类似的不均匀性补偿的第二级别。

公开(公告)号：US4970457A

公开(公告)日：1990-11-13

申请号：US363187

申请日：1989-06-08

申请人： Leon Kaufman ,  Lawrence E. Crooks ,  James D. Hale ,  David M. Kramer ,  Kristen Hake ,  Heckor Avram ,  Joel Wummer

发明人： Leon Kaufman ,  Lawrence E. Crooks ,  James D. Hale ,  David M. Kramer ,  Kristen Hake ,  Heckor Avram ,  Joel Wummer

IPC分类号： A61B5/055 ,  G01R33/48 ,  G01R33/565 ,  G01R33/58

CPC分类号： G01R33/583 ,  G01R33/56563

摘要： Static B.sub.o field strength is measured during each TR interval of an MRI sequence providing field calibration data used to compensate for rapid variations in B.sub.o during the MRI sequence.

公开(公告)号：US4885542A

公开(公告)日：1989-12-05

申请号：US181440

申请日：1988-04-14

申请人： Ching Yao ,  James D. Hale ,  Lawrence E. Crooks ,  Leon Kaufman

发明人： Ching Yao ,  James D. Hale ,  Lawrence E. Crooks ,  Leon Kaufman

IPC分类号： A61B5/055 ,  G01R33/48 ,  G01R33/565 ,  G01R33/58

CPC分类号： G01R33/56563 ,  G01R33/56518 ,  G01R33/583

摘要： At least one extra NMR measurement cycle is performed without any imposed magnetic gradients during readout and recordation of the NMR RF response. Calibration data derived from this extra measurement cycle or cycles can be used for resetting the RF transmitter frequency and/or for phase shifting other conventionally acquired NMR RF response data to compensate for spurious changes in magnetic fields experienced during the NMR data measuring processes. Some such spurious fields may be due to drifting of the nominally static magnetic field. Another source of spurious fields are due to remnant eddy currents induced in surrounding conductive structures by magnetic gradient pulses employed prior to the occurrence of the NMR RF response signal. Special procedures can be employed to permit the compensation data itself to be substantially unaffected by relatively static inhomogeneities in the magnetic field and/or by differences in NMR spectra of fat and water types of nuclei in imaged volumes containing both.

公开(公告)号：US20080009701A1

公开(公告)日：2008-01-10

申请号：US11420224

申请日：2006-05-25

申请人： Hector E. Avram ,  James D. Hale ,  Ilya Simovsky ,  David M. Kramer

发明人： Hector E. Avram ,  James D. Hale ,  Ilya Simovsky ,  David M. Kramer

IPC分类号： A61B5/05

CPC分类号： G01R33/56341 ,  G01R33/5608 ,  G01R33/5615 ,  G01R33/5617 ,  G01R33/565 ,  G01R33/56509

摘要： In preferred embodiments, a fast spin echo imaging technique is provided that is insensitive to violations of the Carr Purcell Meiboom Gill (CPMG) condition. Diffusion gradients disrupt the CPMG condition, and, hence, the present fast spin echo method is compatible with diffusion measurements and diffusion weighted imaging. The preferred embodiments of the present technique involve splitting of spin echoes into echo pairs. Spin echoes are split by adjustment (in magnitude or duration) of an initial readout gradient pulse. A train of echo pairs is captured. A first image is constructed using the first echoes of each pair. Also, a second image is constructed using the second echoes of each pair. Hybrid radial Cartesian methods are used for constructing the first and second images. The first and second images are constructed independently of one another. Independent image construction renders the method insensitive to violation of the CPMG condition. Finally, the two images are combined to form a final image.

摘要翻译： 在优选实施例中，提供了对违反Carr Purcell Meiboom Gill（CPMG）条件不敏感的快速自旋回波成像技术。 扩散梯度破坏CPMG条件，因此，本发明的快速自旋回波方法与扩散测量和扩散加权成像兼容。 本技术的优选实施例涉及将自旋回波分解为回波对。 旋转回波通过初始读数梯度脉冲的调整（幅度或持续时间）分割。 一串回波对被捕获。 使用每对的第一个回波构建第一个图像。 此外，使用每对的第二回波来构建第二图像。 混合径向笛卡尔方法用于构建第一和第二图像。 第一和第二图像彼此独立构建。 独立的图像构造使得方法对违反CPMG条件不敏感。 最后，将两张图像合并形成最终图像。