MYOCARDIAL FUNCT USING SPATIOTEMPORAL FINITE ELEMENT MESH MODEL & VELOCITY DATA

攻略：相衬速度数据可以用来计算 心肌区域的运动和变形。我们提出了一种方法 它使用全球时空有限元模型来改进 计算的重复性，同时保持高精度，如 与局部计算方法相比。方法和结果：我们 考虑一个大心肌区域的分区，其中 非重叠时变基本网格单元。的节点数 在参考状态下选择覆盖该区域的网格。这些 物质点和相应的时空轨迹定义 每个网格单元的时变域。在每个元素中，我们 使用有限元形函数对运动学进行建模。在……里面 实现，其参考状态网格配置由 用户，以及后续网格配置的初始估计 通过对节点的独立跟踪获得，迭代求精 通过将速度数据拟合到 时空有限元模型。计算机的可重复性 可以在每次计算后进行数量分析。在一个 验证研究，我们合成了一个二维非均匀变形数据集 其近似信噪比为45。我们计算了运动和变形 在情况1中分析单个三角形网格单元的土方量 以及分析扩展网状结构，该扩展网状结构包括 相同元素加上可比较元素的另外三个相邻元素 案例2中的大小。重复1000次数据合成和分析 对于平均值和标准差的测量显示，平均值 估计的数量与真实数量非常吻合 这两种情况下的值。比较相同网格单元的结果 在这两种情况下，扩展网格建模导致 标准偏差较低，但准确度相对较高。摘要和 结论：用本方法分析单个元素结构域 与以前的局部方法具有大致相同的重复性。 在本方法中，有限元网格的扩展是通过添加 更多的三角形元素实现了更高的重复性。在 同时，由于分段参数化，估计值较高 精确度，与当地方法相当，仍然可以 获得。

Introduction: Phase contrast velocity data can be used to compute motion and deformation of a myocardial region. We present a method that uses a global spatiotemporal finite element model to improve the reproducibility of the computation while retain high accuracy, as compared to a local computation method. Methods and Results: We consider a partition of a large myocardial region with non-overlappingtime-varying basic mesh elements. Nodal points of the mesh covering the region are selected at a reference state. These material points and corresponding spatiotemporal trajectories define the time-varying domain of each mesh element. Within each element, we model the kinematics using finite element shape functions. In implementation, with a reference state mesh configuration defined by the user, and initial estimates of the subsequent mesh configurations obtained by independent tracking of node points, we iteratively refine the mesh configuration estimates by fitting the velocity data to the spatiotemporal finite element model. Reproducibility of the computed quantities can be analyzed after after each computation. In a validation study, we synthesized a 2-D nonuniform deformation data set with an apprent SNR of 45. We computed the motion and deformation quantities from analyzing a single triangular mesh element in case 1 and analyzing an extended mesh configuration that consisted of the same element plus three additional neighboring elements of compariable size in case 2. Repeating the data synthesis and analysis 1000 times for mean and standard deviation measurements showed that the averages of the estimated quantities were in excellent agreement with the true values in both cases. Comparing the results for the same mesh element in the two cases indicated that the extended mesh modeling resulted in lower standard deviation but comparably high accuracy. Summary and Conclusion: Analyzing a single element domain with the present method and the previous local method have about the same reproducibility. With the present method, extending the finite element mesh by adding more triangular elements achieves increasing reproducibility. At the same time, due to the piecewise parameterization, high estimation accuracy, comparable to that of the local method, can still be obtained.