Gillam John E, Angelis Georgios I, Meikle Steven R
Faculty of Health Sciences, University of Sydney, New South Wales 2006, Australia. Brain and Mind Centre, Camperdown, New South Wales 2050, Australia.
Phys Med Biol. 2016 Sep 21;61(18):N497-N513. doi: 10.1088/0031-9155/61/18/N497. Epub 2016 Aug 23.
Image space decomposition based on tetrahedral voxels are interesting candidates for use in emission tomography. Tetrahedral voxels provide many of the advantages of point clouds with irregular spacing, such as being intrinsically multi-resolution, yet they also serve as a volumetric partition of the image space and so are comparable to more standard cubic voxels. Additionally, non-rigid displacement fields can be applied to the tetrahedral mesh in a straight-forward manner. So far studies incorporating tetrahedral decomposition of the image space have concentrated on pre-calculated, node-based, system matrix elements which reduces the flexibility of the tetrahedral approach and the capacity to accurately define regions of interest. Here, a list-mode on-the-fly calculation of the system matrix elements is described using a tetrahedral decomposition of the image space and volumetric elements-voxels. The algorithm is demonstrated in the context of awake animal PET which may require both rigid and non-rigid motion compensation, as well as quantification within small regions of the brain. This approach allows accurate, event based, motion compensation including non-rigid deformations.
基于四面体体素的图像空间分解是发射断层扫描中很有吸引力的候选方法。四面体体素具有许多不规则间距点云的优点，例如本质上具有多分辨率，而且它们还作为图像空间的体积划分，因此可与更标准的立方体体素相媲美。此外，非刚性位移场可以直接应用于四面体网格。到目前为止，纳入图像空间四面体分解的研究集中在预先计算的、基于节点的系统矩阵元素上，这降低了四面体方法的灵活性以及准确定义感兴趣区域的能力。在此，描述了一种使用图像空间和体积元素（体素）的四面体分解对系统矩阵元素进行列表模式实时计算的方法。该算法在清醒动物正电子发射断层扫描的背景下得到了验证，清醒动物正电子发射断层扫描可能需要刚性和非刚性运动补偿，以及大脑小区域内的定量分析。这种方法允许进行准确的、基于事件的运动补偿，包括非刚性变形。
