Xiang Q S, Henkelman R M
Department of Medical Biophysics, University of Toronto, Ontario, Canada.
J Magn Reson Imaging. 1992 Nov-Dec;2(6):679-85. doi: 10.1002/jmri.1880020612.
It has been previously shown that an image with motion ghost artifacts can be decomposed into a ghost mask superimposed over a ghost-free image. The present study demonstrates that the ghost components carry useful dynamic information and should not be discarded. Specifically, ghosts of different orders indicate the intensity and phase of the corresponding harmonics contained in the quasi-periodically varying spin-density distribution. A summation of the ghosts weighted by appropriate temporal phase factors can give a time-dependent dynamic image that is a movie of the object motion. This dynamic image reconstruction technique does not necessarily require monitoring of the motion and thus is easy to implement and operate. It also has a shorter imaging time than point-by-point imaging of temporal variation, because the periodic motion is more efficiently sampled with a limited number of harmonics recorded in the motion ghosts. This technique was tested in both moving phantoms and volunteers. It is believed to be useful for dynamic imaging of time-varying anatomic structures, such as in the cardiovascular system.
先前已经表明，带有运动模糊伪影的图像可以分解为叠加在无模糊图像上的模糊掩码。本研究表明，模糊成分携带有用的动态信息，不应被丢弃。具体而言，不同阶的模糊表示准周期性变化的自旋密度分布中所含相应谐波的强度和相位。通过适当的时间相位因子对模糊进行加权求和，可以得到一个随时间变化的动态图像，即物体运动的动态影像。这种动态图像重建技术不一定需要监测运动，因此易于实现和操作。与逐点成像时间变化相比，它的成像时间也更短，因为利用运动模糊中记录的有限数量的谐波可以更有效地对周期性运动进行采样。该技术在运动模型和志愿者身上均进行了测试。据信它对时变解剖结构的动态成像有用，比如在心血管系统中。
