公开(公告)号：US5998996A

公开(公告)日：1999-12-07

申请号：US826183

申请日：1997-03-27

申请人： Matthew A. Bernstein ,  Xiaohang Zhou ,  Kevin F. King ,  Alexander Ganin ,  Gary H. Glover ,  Norbert J. Pelc ,  Jason A. Polzin

发明人： Matthew A. Bernstein ,  Xiaohang Zhou ,  Kevin F. King ,  Alexander Ganin ,  Gary H. Glover ,  Norbert J. Pelc ,  Jason A. Polzin

IPC分类号： G01R33/54 ,  A61B5/055 ,  G01R33/563 ,  G01R33/565 ,  G01V3/00

CPC分类号： G01R33/56581 ,  G01R33/56308

摘要： A method is presented for correcting Maxwell term error artifacts produced by an NMR system during the production of either a phase contrast angiogram or a complex difference angiogram. Phase corrections are made to the reconstructed phase image to eliminate the artifacts. Correction coefficients calculated from the flow encoding magnetic gradient waveforms of the phase contrast pulse sequence are used in a polynomial to calculate a set of phase error corrections. These corrections are then used to adjust the phase at each pixel of the angiogram image.

摘要翻译： 提出了一种用于在生产相位对比血管造影或复杂差异血管造影图中校正由NMR系统产生的麦克斯韦尔术语误差伪像的方法。 对重建的相位图像进行相位校正，以消除伪影。 由相位对比脉冲序列的流量编码磁梯度波形计算的校正系数用于多项式以计算一组相位误差校正。 然后使用这些校正来调整血管造影图像的每个像素处的相位。

公开(公告)号：US4665365A

公开(公告)日：1987-05-12

申请号：US689428

申请日：1985-01-07

申请人： Gary H. Glover ,  Norbert J. Pelc

发明人： Gary H. Glover ,  Norbert J. Pelc

IPC分类号： A61B10/00 ,  A61B5/055 ,  G01R33/48 ,  G01R33/54 ,  G01R33/20

CPC分类号： G01R33/482

摘要： A method for reversing residual transverse magnetization due to spatial encoding magnetic field gradient pulses, used in magnetic resonance imaging to encode spatial information, employs a reversing gradient pulse applied in the same direction as the encoding gradient pulse following the observation of the spin-echo signal. The encoding gradient pulse is applied following the 180.degree. RF pulse to avoid the effects of imperfections associated therewith. In one embodiment, the amplitudes of the encoding and reversing gradient pulses are selected to be approximately the negatives of each other so as to substantially cancel the residual magnetization. In another embodiment, the amplitude of the reversing gradient pulse is selected such that the algebraic sum thereof with the corresponding amplitude of the encoding gradient pulse is a constant. In this case, the residual magnetization is not necessarily cancelled, but rather, is left in the same state after each view of the pulse sequence. The method is applicable to multiple-echo and driven equilibrium pulse sequences.

摘要翻译： 用于在磁共振成像中用于编码空间信息的空间编码磁场梯度脉冲的逆向残余横向磁化强度的方法采用与观察自旋回波信号之后的编码梯度脉冲沿相同方向施加的反转梯度脉冲 。 在180°RF脉冲之后施加编码梯度脉冲，以避免与之相关的缺陷的影响。 在一个实施例中，编码和反转梯度脉冲的幅度被选择为彼此近似为负，从而基本上消除剩余磁化。 在另一个实施例中，选择反转梯度脉冲的幅度，使得其与编码梯度脉冲的对应幅度的代数和是一常数。 在这种情况下，剩余磁化不一定被取消，而是在脉冲序列的每个视图之后保持在相同的状态。 该方法适用于多回波和驱动平衡脉冲序列。

公开(公告)号：US4751462A

公开(公告)日：1988-06-14

申请号：US54348

申请日：1987-05-26

申请人： Gary H. Glover ,  Norbert J. Pelc ,  James R. MacFall

发明人： Gary H. Glover ,  Norbert J. Pelc ,  James R. MacFall

IPC分类号： G01R33/54 ,  A61B5/055 ,  A61B10/00 ,  G01R33/32 ,  G01R33/567 ,  G01R33/20

CPC分类号： G01R33/5673

摘要： A method for reducing image artifacts due to signal variations in the course of examining a subject using nuclear magnetic resonance (NMR) techniques includes the acquisition of NMR data for imaging the object. The NMR data is composed of a number of views. The acquisition of each view includes the implementation of a pulse sequence to generate an NMR signal and application of a magnetic gradient along at least one dimensional axis of the object. A gating technique is used to define a window during a portion of each respiratory cycle and NMR data is acquired only during each window. A view ordering technique is employed during the data acquisition by altering the magnitude of a field gradient in a nonmonotonic manner.

摘要翻译： 在使用核磁共振（NMR）技术检查对象的过程中由于信号变化引起的图像伪像的方法包括获取用于成像对象的NMR数据。 NMR数据由多个视图组成。 每个视图的获取包括实现脉冲序列以产生NMR信号并且沿物体的至少一维轴线施加磁梯度。 门控技术用于在每个呼吸周期的一部分期间定义窗口，并且仅在每个窗口期间获取NMR数据。 通过以非单调方式改变场梯度的幅度，在数据采集期间采用视图排序技术。

公开(公告)号：US4706026A

公开(公告)日：1987-11-10

申请号：US766842

申请日：1985-08-16

申请人： Norbert J. Pelc ,  Gary H. Glover

发明人： Norbert J. Pelc ,  Gary H. Glover

IPC分类号： A61B10/00 ,  A61B5/055 ,  G01R33/48 ,  G01R33/561 ,  G01R33/567 ,  G01R33/20

CPC分类号： G01R33/56509 ,  G01R33/561

摘要： A method for reducing image artifacts due to periodic motion of a subject undergoing examination by nuclear magnetic resoance (NMR) techniques includes the acquisition of scan data for imaging the object. The scan data is composed of a number of views. The acquisition of each view includes the generation of an NMR signal and the application of a magnetic gradient along at least one dimensional axis of the object. The magnetic field gradient is characterized by a parameter value (e.g., amplitude or direction) adjustable from view to view to encode spatial information into the NMR signal. The method includes the step of selecting the value of the adjustable parameter value for each view. A view order is then selected so as to attempt to obtain a predetermined relationship between the object motion and the adjustable parameter of the magnetic field gradient. The relationship is chosen to minimize artifacts in the reconstructed image. The method is applicable to various NMR imaging techniques, including Fourier Transform and multiple angle projection reconstruction.

摘要翻译： 用于通过核磁共振（NMR）技术进行检查的受试者的周期运动减少图像伪影的方法包括获取用于成像对象的扫描数据。 扫描数据由多个视图组成。 每个视图的获取包括产生NMR信号以及沿物体的至少一维轴线施加磁梯度。 磁场梯度的特征在于从视图到视图可调整的参数值（例如，幅度或方向），以将空间信息编码成NMR信号。 该方法包括为每个视图选择可调节参数值的值的步骤。 然后选择视图顺序，以便尝试获得物体运动和磁场梯度的可调整参数之间的预定关系。 选择关系以最小化重构图像中的伪影。 该方法适用于各种NMR成像技术，包括傅里叶变换和多角度投影重建。

公开(公告)号：US4698591A

公开(公告)日：1987-10-06

申请号：US816074

申请日：1986-01-03

申请人： Gary H. Glover ,  Norbert J. Pelc

发明人： Gary H. Glover ,  Norbert J. Pelc

IPC分类号： G01R33/20 ,  A61B5/05 ,  A61B5/055 ,  A61B10/00 ,  G01R33/385 ,  G01R33/48 ,  G01R33/565

CPC分类号： G01R33/56518 ,  G01R33/385

摘要： A method is provided for characterizing the spurious, time-dependent magnetic field gradient response and for compensating therefor. In accordance with the method a small sample object is placed away from the system isocenter where the gradient to be compensated is non-zero. A magnetic field gradient pulse is applied to the sample, followed by the application after a variable time of a 90.degree. radio frequency pulse. The phase of the resulting free induction decay (FID) signal is monitored as a function of total time since the end of the gradient pulse. These data are related to the gradient impulse response and are fit to a set of (e.g., two or three) exponentials by regression techniques wherein an initial estimate is improved in one embodiment by chi-squared minimization of a Taylor's series expansion about the initial estimate point.

摘要翻译： 提供一种用于表征寄生的，时间依赖的磁场梯度响应并用于补偿的方法。 根据该方法，将小的样品物体放置在远离系统等角点，其中待补偿的梯度不为零。 对样品施加磁场梯度脉冲，然后在90°射频脉冲的可变时间之后施加磁场梯度脉冲。 从梯度脉冲结束开始，监测所得到的自由感应衰减（FID）信号的相位作为总时间的函数。 这些数据与梯度脉冲响应相关，并且通过回归技术适合于一组（例如，两个或三个）指数，其中在一个实施例中，通过关于初始估计的泰勒级数展开的卡方最小化来改善初始估计 点。

公开(公告)号：US4554633A

公开(公告)日：1985-11-19

申请号：US428771

申请日：1982-09-30

申请人： Gary H. Glover ,  Dennis G. DallaPiazza ,  Norbert J. Pelc

发明人： Gary H. Glover ,  Dennis G. DallaPiazza ,  Norbert J. Pelc

IPC分类号： G06T11/00 ,  G06F15/42 ,  G01T1/17

CPC分类号： G06T11/005 ,  Y10S378/901

摘要： A CT scanner in which the amount of x-ray information acquired per unit time is substantially increased by using a continuous-on x-ray source and a sampled data system with the detector. An analog filter is used in the sampling system for band limiting the detector signal below the highest frequency of interest, but is a practically realizable filter and is therefore non-ideal. A digital filter is applied to the detector data after digitization to compensate for the characteristics of the analog filter, and to provide an overall filter characteristic more nearly like the ideal.

摘要翻译： 其中通过使用连续的x射线源和采样的数据系统与检测器相比，每单位时间获取的X射线信息量大幅增加的CT扫描器。 在采样系统中使用模拟滤波器将检测器信号的频带限制在感兴趣的最高频率之下，但是实际上是可实现的滤波器，因此是非理想的。 数字滤波器在数字化后应用于检测器数据，以补偿模拟滤波器的特性，并提供更接近于理想的整体滤波器特性。

公开(公告)号：US4550371A

公开(公告)日：1985-10-29

申请号：US424501

申请日：1982-09-27

申请人： Gary H. Glover ,  Norbert J. Pelc

发明人： Gary H. Glover ,  Norbert J. Pelc

IPC分类号： G01N23/04 ,  A61B6/03 ,  G06T11/00 ,  A61B6/00

CPC分类号： G06T11/005 ,  A61B6/5258 ,  G06T2211/432

摘要： A method and apparatus for compensating CT images for truncated projections created when an object extends beyond the field of view during the course of collecting a set of projections. Projections which have reference channel information influenced by the object are identified, and the reference channel information thereof replaced by more accurate information derived from unaffected projections. The zero and first order moments of the projection set are analyzed to better estimate the expected moments had the truncated projections not been truncated, and to use that information in completing the truncated projections. A closed form solution is used for convolution of the extensions of the truncated projections to avoid substantial delays in processing the final CT image.

摘要翻译： 一种用于在收集一组突起的过程中当物体延伸超出视场时产生的用于补偿CT图像的方法和装置。 识别具有受对象影响的参考信道信息的投影，并且将其参考信道信息替换为从未受影响的投影导出的更准确的信息。 分析投影集的零和一阶矩，以更好地估计截短的投影未被截断的预期时刻，并使用该信息来完成截断的投影。 闭合形式的解决方案用于卷曲截断投影的延伸部分，以避免处理最终CT图像的实质性延迟。

公开(公告)号：US6144873A

公开(公告)日：2000-11-07

申请号：US62295

申请日：1998-04-17

申请人： Bruno Madore ,  Gary H. Glover ,  Norbert J. Pelc

发明人： Bruno Madore ,  Gary H. Glover ,  Norbert J. Pelc

IPC分类号： G01R33/561 ,  A61B5/055

CPC分类号： G01R33/561 ,  G01R33/4824 ,  G01R33/56308

摘要： MRI is used to monitor the time behavior or an organ of interest. Images of such organ may change in time due to physiological motion, and/or due to contrast-agent accumulation. Dynamic applications generally involve acquiring data in a k-t space, which contains both temporal and spatial information. In some dynamic applications, the t axis of the k-t space is not densely filled with information. A method is introduced which can transfer information from the k axes to the t axis, allowing a denser, smaller k-t space to be acquired, and leading to significant reductions in the acquisition time of the temporal frames. Results are presented for cardiac imaging and functional MRI (fMRI). In the case of cardiac imaging, the present method is shown to reduce the data requirement by nearly a factor two. In the case of fMRI, reductions by as much as a factor six can be obtained. The behavior of the method is assessed by comparing the results to data obtained in a conventional way. Of course, the reductions in imaging time lead to the expected reductions in SNR. The present method can be used to significantly reduce the acquisition time of the individual temporal frames in certain dynamic studies. This can be used, for example, to increase the temporal and/or spatial resolution, increase the spatial coverage, decrease the total imaging time, or alter sequence parameters (e.g., TR and TE) and thereby alter contrast, depending on the circumstances.

摘要翻译： MRI用于监测时间行为或感兴趣的器官。 由于生理运动，和/或由于造影剂累积，这种器官的图像可能在时间上改变。 动态应用通常涉及在包含时间和空间信息的k-t空间中获取数据。 在某些动态应用中，k-t空间的t轴不是密集填充信息。 引入了一种可以将信息从k轴传递到t轴的方法，允许获取更密集，更小的k-t空间，并导致时间帧的采集时间的显着减少。 结果用于心脏成像和功能MRI（fMRI）。 在心脏成像的情况下，本方法显示将数据需求减少近二分之一。 在功能磁共振成像的情况下，可以获得多达六分之一的减少。 通过将结果与以常规方式获得的数据进行比较来评估该方法的行为。 当然，成像时间的减少导致SNR的预期降低。 本方法可用于在某些动态研究中显着减少单个时间帧的采集时间。 这可以例如用于增加时间和/或空间分辨率，增加空间覆盖率，减少总成像时间，或改变序列参数（例如，TR和TE），从而根据情况改变对比度。

公开(公告)号：US4950994A

公开(公告)日：1990-08-21

申请号：US164687

申请日：1988-03-07

申请人： Gary H. Glover ,  Norbert J. Pelc ,  Kenneth Marel Bradshaw

发明人： Gary H. Glover ,  Norbert J. Pelc ,  Kenneth Marel Bradshaw

IPC分类号： G01R33/48 ,  A61B5/055 ,  G01R33/32 ,  G01R33/385 ,  G01R33/3875 ,  G01R33/54

CPC分类号： G01R33/385 ,  G01R33/3875

摘要： A method is provided for characterizing the spurious, time dependent magnetic field gradient response and for compensating therefor. In accordance with the method, two small sample objects are placed at two positions with respect to the system isocenter where the gradient to be compensated has different values. A magnetic field gradient pulse is applied to the sample, followed by the application after a variable time of a 90.degree. radio frequency pulse. The phase of the resulting free induction decay (FID) signal is monitored as a function of total time since the end of the gradient pulse. These data are related to the impulse response of the gradient and are employed to construct compensation filters for both the gradient coils and the polarizing field shim coil.

公开(公告)号：US4710717A

公开(公告)日：1987-12-01

申请号：US947211

申请日：1986-12-29

申请人： Norbert J. Pelc ,  Gary H. Glover

发明人： Norbert J. Pelc ,  Gary H. Glover

IPC分类号： A61B5/055 ,  A61B10/00 ,  G01R33/48 ,  G01R33/561 ,  G01R33/567 ,  G01R33/20

CPC分类号： G01R33/56325 ,  G01R33/567

摘要： An NMR method for producing a sequence of images throughout the cardiac cycle is disclosed. A fast scan NMR pulse sequence is continuously and asynchronously applied during successive cardiac cycles, and a phase encoding magnetic field gradient is incremented between cardiac cycles to acquire NMR data which is reconstructed using a 2DFT technique. The phase encoding magnetic field gradient is stepped in subincrements, and the odd and even phase encoding views are acquired in separate segments of the procedure in order to eliminate image distortion due to disturbance of the residual transverse magnetization.