Correcting corrupted-phases by blood perfusion, diffusion and body motion in MRI imaging.

纠正 MRI 成像中血液灌注、扩散和身体运动造成的损坏相位。

基本信息

批准号：
04650314
负责人：
TAMURA Shinichi
金额：
$ 1.41万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

When taking perfusion or diffusion images of small flow, artifact is easily caused by body motion. In this research, we developed artifact correction algorithms for translational, rotational, and expanding-shrinking body motions.(1) Translational rigid body motion : Using the fact that Fourier transform F (x, n) of MRI signal f (x, n) in the n-th view (phase encode) shows the object position along the frequency axis (x), we corrected the corrupted phases by a body motion. We have also developed a method which can correct independently of x-axis the body motion alosng y-axis.(2) Rotational rigid body motion : For a step rotation with unkown rot ation center and rotation angle, first we estimated the rotaion angle so that energy in outside region of the reconstructed image becomes minimum. Then we applied the phase retreaval algorithm to reduce the phase disturbance caused by the off-origin of the rotation center.(3) Expanding-shrinking deformable body motion : In case of such as abdomen expanding and shrinking proportionally in x-and y-axs, we have shown that we can reduce the artifact by ; first obtain x-directional motion from the projection onto the frequency axis as the same as (1), and then correct phases corresponding to y-axis by the phase retreaval algorithm.These algorithms can also be applied to the artifact correction caused by body motion of child and old person who cannot lay still for the image taking time of several to several ten minutes with conventional MRI.In order to make the algorithm more close to the practical use, it's a future task to model the more flexible motion with more number of freedom.

当拍摄灌注或较小流动的扩散图像时，伪影很容易由身体运动引起。在这项研究中，我们开发了用于翻译，旋转和扩大骨架身体运动的人工校正算法。（1）转化刚性的身体运动：使用以下事实：N-th视图（相位编码）中MRI信号F（x，n）的MRI信号F（x，n）的傅立叶变换f（x，n）沿频率轴（x）表现出损坏的体阶段，我们对物体的位置显示了损坏的阶段。我们还开发了一种可以独立于x轴运动的方法。（2）旋转刚性身体运动：对于带有未镇定腐烂中心和旋转角的阶跃旋转，首先，我们估计了旋转角度，因此，在重建图像的外部区域中的旋转角度最低。然后，我们应用了相后方算法，以减少由旋转中心的异生蛋白产生的相位障碍。（3）扩大缩减可变形的身体运动：在诸如腹部相-Axs中腹部膨胀和缩小X和Y轴的缩小时，我们已经表明，我们可以减少工件的减少;首先，从投影到频率轴的x方向运动与（1）相同，然后通过相位逆转录算法对应于y轴对应于y轴的正确阶段。这些算法也可以应用于因童装而导致的，这些算法的校正也可以是由幼体和老年人的身体运动引起的，这些算法仍然无法与其他数分钟相关的时间，以使其与数分差不多的序列相关。未来的任务，以更多的自由度建模更灵活的运动。