公开(公告)号：US4743851A

公开(公告)日：1988-05-10

申请号：US89941

申请日：1987-08-25

申请人： Arthur J. Lim ,  Michael H. Buonocore ,  Craig H. Barratt

发明人： Arthur J. Lim ,  Michael H. Buonocore ,  Craig H. Barratt

IPC分类号： G01N24/08 ,  G01R33/385 ,  G01R33/54 ,  G01R33/20

CPC分类号： G01R33/56518 ,  G01N24/08 ,  G01R33/4833

摘要： In an improved NMR imaging method for forming images of a subject by determining the relative densities of nuclei within the subject, three orthogonal gradient fields are generated by digitally storing three gradient waveforms for each orthogonal direction, with each waveform being individually compensated and calibrated with respect to an axis with which it is associated. Nine associated matrix multiplying functions which determine the coordinates of a desired slice in its rotated plane are also stored by an external input (by computer or by the clinician operating the system.) Then, in a sequential fashion, digital words for each gradient waveform are read out, multiplied by pairs with the appropriate multiplying function and the three terms are added to form a digital word. These words are converted to an analog value and applied to the respective gradient coils.

摘要翻译： 在用于通过确定受试者中核的相对密度来确定受试者的图像的改进的NMR成像方法中，通过对每个正交方向数字地存储三个梯度波形来产生三个正交梯度场，每个波形被单独地补偿和校准， 与其相关联的轴。 确定其旋转平面中期望切片的坐标的九个相关联的矩阵乘法函数也由外部输入（由计算机或由操作系统的临床医师）存储。然后，以顺序的方式，每个梯度波形的数字字是 读出，乘以具有适当乘法函数的对，并且添加三个项以形成数字字。 将这些字转换为模拟值并应用于各个梯度线圈。

公开(公告)号：US4651096A

公开(公告)日：1987-03-17

申请号：US702966

申请日：1985-02-19

申请人： Michael H. Buonocore

发明人： Michael H. Buonocore

IPC分类号： G01R33/54 ,  G01R33/561 ,  G01R33/20

CPC分类号： G01R33/4824 ,  G01R33/4835 ,  G01R33/561

摘要： There is disclosed an improved NMR imaging method utilized for forming images of a subject by determining the relative densities of nuclei within the subject. A main magnetic field is applied to the subject to create aligned nuclear spins in the nuclei. Radio frequency energy is applied to the subject at a predetermined Larmor frequency to create a radio frequency field acting in a direction substantially perpendicular to the main magnetic field. A gradient magnetic field is applied to the subject along a selected axis at a time substantially coincident to the time of application of the radio frequency energy so that the nuclei in only a thin slice of the subject are excited. The application of radio frequency energy is terminated after a predetermined time. Thereafter, two time varying balanced gradient magnetic fields are applied to the subject along two perpendicular axes, which are both perpendicular to the first magnetic gradient field. The resulting precession of the nuclear spins is detected during substantially the entire time of the free induction decay period of the spins. An image is then formed from the detected information. These steps are repeated so that many slices of the subject are imaged substantially simultaneously.

摘要翻译： 公开了通过确定受试者内核的相对密度而用于形成受试者图像的改进的NMR成像方法。 将主磁场施加到受试者以在核中产生对准的核自旋。 以预定的拉莫尔频率将射频能量施加到被摄体，以产生沿与主磁场基本垂直的方向作用的射频场。 在与施加射频能量的时间基本上一致的时间沿着选定的轴施加梯度磁场，使得仅对象的薄片中的核被激发。 无线电频率能量的应用在预定时间之后终止。 此后，两个时变平衡梯度磁场沿两个垂直于第一磁梯度场的垂直轴施加到被摄体。 在旋转的自由感应衰减期的大部分时间内检测到所得到的核自旋的进动。 然后根据检测到的信息形成图像。 重复这些步骤，使得受试者的许多切片基本上同时成像。