公开(公告)号：US06452387B1

公开(公告)日：2002-09-17

申请号：US09801424

申请日：2001-03-07

申请人： Brain A. Hargreaves ,  Shreyas Vasanawala ,  John M. Pauly ,  Dwight G. Nishimura

发明人： Brain A. Hargreaves ,  Shreyas Vasanawala ,  John M. Pauly ,  Dwight G. Nishimura

IPC分类号： G01V300

CPC分类号： G01R33/5613

摘要： A steady-state condition for tipped nuclear spins is accelerated or catalyzed by first determining magnetization magnitude of the steady state and the scaling magnetization along one axis (Mz) to at least approximate the determined magnetization magnitude. Then the scaled magnetization is rotated to coincide with a real-valued eigenvector extension of the tipped steady-state magnetization. Any error vector will then decay to the steady-state condition without oscillation. In one embodiment, the magnetic resonance imaging utilizes steady-state free precession (SSFP). The scaling and rotating steps are followed by the steps of applying read-out magnetic gradients and detecting magnetic resonance signals from the tipped nuclear spins. The magnetization magnitude is determined by eigenvector analysis, and the eigenvector extension is a real-valued eigenvector determined in the analysis.

摘要翻译： 通过首先确定稳态的磁化强度和沿着一个轴（Mz）的缩放磁化强度至少接近确定的磁化强度，来加速或催化尖端核自旋的稳态条件。 然后，缩放的磁化被旋转以与尖端稳态磁化的实数特征向量延伸一致。 任何误差矢量都会衰减到稳态，而不会产生振荡。 在一个实施例中，磁共振成像利用稳态自由进动（SSFP）。 缩放和旋转步骤之后是应用读出磁梯度并从尖端核自旋检测磁共振信号的步骤。 磁化强度由特征向量分析确定，特征向量扩展是在分析中确定的实值特征向量。

公开(公告)号：US06307368B1

公开(公告)日：2001-10-23

申请号：US09312025

申请日：1999-05-14

申请人： Shreyas S. Vasanawala ,  John M. Pauly ,  Dwight G. Nishimura

发明人： Shreyas S. Vasanawala ,  John M. Pauly ,  Dwight G. Nishimura

IPC分类号： G01V300

CPC分类号： G01R33/5613 ,  G01R33/446

摘要： A fast, spectrally-selective steady-state free precession (SSFP) imaging method is presented. Combining k-space data from SSFP sequences with certain phase schedules of radiofrequency excitation pulses permits manipulation of the spectral selectivity of the image. For example, lipid and water can be rapidly resolved. The contrast of each image depends on both T1 and T2, and the relative contribution of the two relaxation mechanisms to image contrast can be controlled by adjusting the flip angle. Several applications of the technique are presented, including fast musculoskeletal imaging, brain imaging, and angiography. The technique is referred to herein as linear combination steady-state free precession (LCSSFP) and fluctuating equilibrium magnetic resonance (FEMR).

摘要翻译： 提出了一种快速，频谱选择性的稳态自由进动（SSFP）成像方法。 将来自SSFP序列的k空间数据与射频激发脉冲的某些相位调度组合允许操纵图像的光谱选择性。 例如，脂质和水可以快速解决。 每个图像的对比度取决于T1和T2，并且可以通过调整翻转角度来控制两个松弛机制对图像对比度的相对贡献。 提出了该技术的几个应用，包括快速肌肉骨骼成像，脑成像和血管造影。 该技术在此被称为线性组合稳态自由进动（LCSSFP）和波动平衡磁共振（FEMR）。

公开(公告)号：US06256526B1

公开(公告)日：2001-07-03

申请号：US09191316

申请日：1998-11-13

申请人： Rosemary K. Butts ,  John M. Pauly

发明人： Rosemary K. Butts ,  John M. Pauly

IPC分类号： A61B5055

CPC分类号： G01R33/285 ,  G01R33/4833

摘要： The present invention provides methods for adjustment of contrast of magnetic susceptibility variations where the variations cause distortions which are removed by view angle tilting. Often, magnetic susceptibility variations are caused by devices such as needles inserted into a patient. In two methods of the present invention, first and second field gradients are applied simultaneous with excitation and refocusing gradients, respectively. The first and second gradients have different amplitudes or orientations, or both. This results in fewer spins rephasing in the vicinity of the susceptibility variation than elsewhere, thereby providing contrast. In another embodiment of the invention, a spin echo is produced, and the detection time of the spin echo signal is offset from the time of the spin echo. The offset results in a phase cancellation of spins near the susceptibility variation due to the relatively large range of magnetic field strengths. Other methods of the present invention are also disclosed.

摘要翻译： 本发明提供了用于调整磁化率变化的对比度的方法，其中变化引起通过视角倾斜移除的失真。 通常，磁化率变化是由诸如插入病人的针的装置引起的。 在本发明的两种方法中，第一和第二场梯度分别与激发和重聚焦梯度同时应用。 第一和第二梯度具有不同的振幅或方向，或两者都是不同的。 这导致在其他地方的敏感性变化附近的旋转重新缩小，从而提供对比度。 在本发明的另一个实施例中，产生自旋回波，并且自旋回波信号的检测时间偏离自旋回波的时间。 由于磁场强度相对较大，偏移导致磁化率变化附近的自旋相位消除。 还公开了本发明的其它方法。

公开(公告)号：US5499629A

公开(公告)日：1996-03-19

申请号：US191342

申请日：1994-02-01

申请人： Adam B. Kerr ,  John M. Pauly

发明人： Adam B. Kerr ,  John M. Pauly

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

CPC分类号： G01R33/446 ,  G01R33/586

摘要： Selective RF pulses are applied for segmented k-space imaging sequences with the tip-angle profiles of the pulses varying for stabilizing the entire signal profile and reducing ghosting and blurring artifacts in slice images.

摘要翻译： 选择性RF脉冲被应用于分段的k空间成像序列，其中脉冲的尖角分布变化以稳定整个信号分布并减少切片图像中的重影和模糊伪像。

公开(公告)号：US5257626A

公开(公告)日：1993-11-02

申请号：US921804

申请日：1992-07-28

申请人： Norbert J. Pelc ,  Douglas C. Noll ,  John M. Pauly

发明人： Norbert J. Pelc ,  Douglas C. Noll ,  John M. Pauly

IPC分类号： G01R33/561 ,  G01R33/563 ,  G01R33/567 ,  A61B5/055 ,  A61B8/00

CPC分类号： G01R33/563 ,  G01R33/5617 ,  G01R33/56316 ,  G01R33/5676

摘要： Measures of a velocity component during a plurality of time frames of cyclical motion of a region of interest are obtained using contrast cine MRI techniques. Trajectories of the region of interest are calculated in a backward direction and in a forward direction. The trajectories are then combined to define a motion trajectory. The forward and backward trajectories are weighted prior to combining with the forward trajectory being more heavily weighted for early frames and the backward trajectory being more heavily weighted for late frames.

摘要翻译： 使用对比电影MRI技术获得感兴趣区域的循环运动的多个时间帧期间的速度分量的测量。 在向后方向和向前方向上计算感兴趣区域的轨迹。 然后组合轨迹以定义运动轨迹。 前向和后向轨迹在组合之前被加权，前向轨迹对于早期帧是更加重的，并且后向轨迹对于后期帧更加重。

公开(公告)号：US5105152A

公开(公告)日：1992-04-14

申请号：US497226

申请日：1990-03-22

申请人： John M. Pauly

发明人： John M. Pauly

IPC分类号： G01R33/48

CPC分类号： G01R33/446

摘要： Disclosed is a method of generating a linear large tip-angle selective excitation pulse for magnetic resonance imaging using a linear Fourier transform analysis. An inherently refocused small tip-angle excitation pulse which produces a rotation about an axis is first defined. Then a sequence of the small tip-angle excitation pulses is produced and concatenated whereby the sum of the tip angles produced by the sequence of pulses results in a desired net large tip-angle. The small tip-angle pulses have a Hermitian RF weighted k-space trajectory. The tip angle is the Fourier transform of the weighted k-space trajectory.

摘要翻译： 公开了使用线性傅里叶变换分析来生成用于磁共振成像的线性大尖角选择激励脉冲的方法。 首先确定产生围绕轴的旋转的固有重新聚焦的小尖角激励脉冲。 然后产生并连接小尖角激励脉冲的序列，由此由脉冲序列产生的尖角的和导致期望的净大尖端角。 小尖角脉冲具有Hermitian RF加权k空间轨迹。 尖角是加权k空间轨迹的傅里叶变换。

公开(公告)号：US4985677A

公开(公告)日：1991-01-15

申请号：US370403

申请日：1989-06-22

申请人： John M. Pauly

发明人： John M. Pauly

IPC分类号： G01R33/48

CPC分类号： G01R33/446

摘要： A method of obtaining multi-dimensional spatially-selective magnetic resonance signals from a body includes applying a static magnetic field (Bo) to said body thereby aligning nuclear spins along an axis (z), and applying one or more time-varying magnetic gradients (Gx(t), Gy(t), Gz(t)) during a time period, T. During the time period, T, an RF excitation pulse (B.sub.1) is applied to said body to tip said nuclear spins, said RF excitation pulse being related to said modulated magnetic gradients by a first spatial frequency weighting function (W(k)(t)) whereby magnetic resonance signals transmitted by said tipped nuclear spins are spatially selective in multi dimensions. The resulting magnetic resonance signals are then detected to provide the multi-dimensional spatially-selective signals.

摘要翻译： 从身体获得多维空间选择性磁共振信号的方法包括将静磁场（Bo）施加到所述主体，从而沿轴（z）对准核自旋，并施加一个或多个时变磁梯度 Gx（t），Gy（t），Gz（t））。在该时间段期间，T将RF激励脉冲（B1）施加到所述主体以使所述核自旋尖端，所述RF激励 脉冲通过第一空间频率加权函数（W（k）（t））与所述调制的磁梯度相关，由此由所述倾斜的核自旋发射的磁共振信号在多维空间上是选择性的。 然后检测所得磁共振信号以提供多维空间选择信号。