公开(公告)号：US5168227A

公开(公告)日：1992-12-01

申请号：US693895

申请日：1991-05-01

申请人： Thomas K. Foo ,  Beth E. Slayman

发明人： Thomas K. Foo ,  Beth E. Slayman

IPC分类号： A61B5/055 ,  G01R33/48 ,  G01R33/56

CPC分类号： G01R33/56

摘要： An NMR system acquires a series of spin-echo signals during a scan and these are used to reconstruct an image. The spin-echo signals are partially acquired by locating the data acquisition window asymmetrically with respect to the echo peak. A homodyne reconstruction is employed to fill in the missing data during the image reconstruction.

公开(公告)号：US5416412A

公开(公告)日：1995-05-16

申请号：US129822

申请日：1993-09-30

申请人： Beth E. Slayman ,  Kevin F. King ,  Paul E. Licato

发明人： Beth E. Slayman ,  Kevin F. King ,  Paul E. Licato

IPC分类号： G01R33/48 ,  A61B5/055 ,  G01R33/54 ,  G01R33/561 ,  G01R33/58 ,  G01R33/20

CPC分类号： G01R33/583 ,  G01R33/54 ,  G01R33/561 ,  G01R33/586

摘要： A prescan for an MRI system (FIG. 1) automatically sets the rf power level to produce an excitation field that nutates spins in the image plane the amount prescribed by the scan. Nutation angle is measured with a pulse sequence comprised of three slice selective excitation pulses that produce a set of frequency encoded NMR echo signals (E.sub.1, S.sub.1, E.sub.2, E.sub.23, E.sub.13). Nutation angle is calculated at locations in the image slice from the Fourier transformation of these signals and the maximum nutation angle is employed to calculate the final rf power level setting for the scan.

摘要翻译： 用于MRI系统的预扫描（图1）自动设置射频功率电平以产生激励场，该激励场将图像平面中的旋转拟合为扫描规定的量。 营养角度是由产生一组频率编码的NMR回波信号（E1，S1，E2，E23，E13）的三个切片选择性激发脉冲组成的脉冲序列测量的。 在这些信号的傅里叶变换的图像切片中的位置处计算营养角度，并且采用最大章动角来计算扫描的最终射频功率电平设置。