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公开(公告)号：US5258711A
公开(公告)日：1993-11-02
申请号：US871154
申请日：1992-04-20
申请人： Christopher J. Hardy
发明人： Christopher J. Hardy
CPC分类号： G01R33/4833
摘要： A method for reducing distortion in magnetic resonance (MR) images of a subject employs distortion compensating MR pulses in a conventional MR imaging sequence. The distortion compensating pulses are determined by first creating a conventional MR image of a slice of a subject having inherent distortions; constructing a target slice which is distorted in a manner opposite the direction of distortions in the slice image; taking a multi-dimensional Fourier transformation of the target slice to obtain a k-space region; choosing a continuous trajectory which efficiently traverses the k-space region; applying principles of multidimensional selective-excitation design to create simultaneous RF pulses and magnetic field gradient waveforms from the trajectory; and simultaneously applying the RF pulses and gradient waveforms in place of a traditional slice-select pulse in conventional MR imaging sequences to obtain images having reduced distortion as compared with conventional images.
摘要翻译： 用于减少受试者的磁共振（MR）图像中的失真的方法使用常规MR成像序列中的失真补偿MR脉冲。 通过首先创建具有固有失真的对象的切片的常规MR图像来确定失真补偿脉冲; 构造以与切片图像中的失真方向相反的方式失真的目标切片; 对目标切片进行多维傅里叶变换以获得k空间区域; 选择有效穿过k空间区域的连续轨迹; 应用多维选择激励设计的原理，从轨迹创建同时的RF脉冲和磁场梯度波形; 并且在常规MR成像序列中同时施加RF脉冲和梯度波形来代替传统的切片选择脉冲，以获得与常规图像相比具有减小的失真的图像。
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公开(公告)号：US5201311A
公开(公告)日：1993-04-13
申请号：US927780
申请日：1992-08-10
IPC分类号： G01R33/483 , G01R33/485
CPC分类号： G01R33/485 , G01R33/483
摘要： A method for providing information about the rate of a selected chemical reaction in each of at least one selected volume elements (voxels) in a sample includes the steps of: exciting a reaction-rate-dependent chemical-shift spectrum, by a selected stimulus (such as one of saturation-transfer and inversion-transfer RF signal pulses) to label the NMR signal of a first reaction constituent; spatially localizing the NMR response signal, provided by the excited resonance, to a selected voxel within the sample; and acquiring and processing the NMR response data from the localized voxel. The excitation, localization and data acquisition subsequences are repeated to generate data substantially proportional, or equal, to the reaction rate constants in the selected voxels, and in planes and/or volumes thereof.
摘要翻译： 提供关于样品中至少一个选定的体积元素（体素）中的每一个中选择的化学反应的速率的信息的方法包括以下步骤：通过所选择的刺激（激发反应速率依赖的化学位移谱） 例如饱和转移和反转传输RF信号脉冲之一）来标记第一反应成分的NMR信号; 将由激发谐振提供的NMR响应信号空间定位到样品内的选定体素; 并从局部体素获取和处理NMR响应数据。 重复激发，定位和数据采集子序列以产生与所选择的体素中的反应速率常数以及其平面和/或体积基本成比例或相等的数据。
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23.发明授权Quantitative measurement of blood flow using cylindrically localized Fourier velocity encoding 失效使用圆柱体局部化的速度编码对血液流量的定量测量
公开(公告)号：US5133357A
公开(公告)日：1992-07-28
申请号：US651872
申请日：1991-02-07
CPC分类号： A61B5/7257 , A61B5/0263 , G01R33/563 , A61B5/7285 , G01R33/446
摘要： A method of imaging and quantitatively measuring blood velocity distribution within a selected vessel employs Nuclear Magnetic Resonance cylindrical excitation of the sample to be imaged, followed by Fourier velocity encoding excitation along a second axis for selectively encoding molecules based upon their flow velocities, then sensing the re-radiated signal data acquired in the presence of a readout gradient to provide resolution along the cylindrical axis, and reconstructing a velocity profile. Spatial localization is accomplished with an excitation pulse having a cylindrical rather than slab geometry. This method can be combined with cardiac synchronization to measure flow dynamics or it can be applied without synchronization to measure steady flow. The geometry of the measurement is flexible in that the directions of flow sensitivity and geometric resolution are independent.
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公开(公告)号：US4812760A
公开(公告)日：1989-03-14
申请号：US78427
申请日：1987-07-27
CPC分类号： G01R33/446
摘要： A single rotating NMR .pi. pulse provides simultaneous spatially-selective inversion or spin-echo refocussing of nuclear pins in two orthogonal dimensions. The two-dimensional spatially-selective pulse utilizes a single RF pulse, with either a square of an amplitude-modulated or a frequency-modulated envelope, and applied in the presence of an amplitude-modulated magnetic field gradient which reorients through the desired dimensions in which selection is desired while the RF pulse is present. These rotating, or ".rho.", pulses are useful for reduction of aliasing signal artifacts is restricted field-of-view high-resolution NMR imaging and, when combined with one-dimensional-localized chemical shift spectroscpoy techniques (such as those employing surface detection coils) is especially useful for the production of three-dimensionally localized NMR spectra. Substantial suppression of undesirable residual excited signals, arising from outside the desired two-dimensional spatially selected region, can be obtained by simulated annealing optimization of both the RF and magnetic field gradient amplitude portions of the .rho. pulse and/or by use of surface coil detection. The location of the selected volume is varied by frequency modulation of the RF signal pulse, or by variation of the ratio of currents in the halves of the magnetic field gradient coils.
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