Mair B A, Gilland David R, Sun Jing
Department of Mathematics, University of Florida, Gainesville, FL 32611, USA.
IEEE Trans Med Imaging. 2006 Sep;25(9):1130-44. doi: 10.1109/tmi.2006.879323.
In this paper, we propose and test a new iterative algorithm to simultaneously estimate the nonrigid motion vector fields and the emission images for a complete cardiac cycle in gated cardiac emission tomography. We model the myocardium as an elastic material whose motion does not generate large amounts of strain. As a result, our method is based on minimizing an objective function consisting of the negative logarithm of a maximum likelihood image reconstruction term, the standard biomechanical model of strain energy, and an image matching term that ensures a measure of agreement of intensities between frames. Simulations are obtained using data for the four-dimensional (4-D) NCAT phantom. The data models realistic noise levels in a typical gated myocardial perfusion SPECT study. We show that our simultaneous algorithm produces images with improved spatial resolution characteristics and noise properties compared with those obtained from postsmoothed 4-D maximum likelihood methods. The simulations also demonstrate improved motion estimates over motion estimation using independently reconstructed images.
在本文中，我们提出并测试了一种新的迭代算法，用于在门控心脏发射断层扫描中同时估计完整心动周期的非刚性运动矢量场和发射图像。我们将心肌建模为一种弹性材料，其运动不会产生大量应变。因此，我们的方法基于最小化一个目标函数，该目标函数由最大似然图像重建项的负对数、应变能的标准生物力学模型以及一个图像匹配项组成，该图像匹配项确保各帧之间强度的一致性度量。使用四维（4-D）NCAT体模的数据进行模拟。该数据模拟了典型门控心肌灌注单光子发射计算机断层扫描（SPECT）研究中的实际噪声水平。我们表明，与通过后平滑四维最大似然方法获得的图像相比，我们的同步算法产生的图像具有更好的空间分辨率特性和噪声特性。模拟还表明，与使用独立重建图像的运动估计相比，运动估计得到了改进。
