MYOCARDIAL FUNCT USING SPATIOTEMPORAL FINITE ELEMENT MESH MODEL & VELOCITY DATA

介绍：相位衬度速度数据可用于计算 心肌区域的运动和变形。 我们提出了一种方法 该模型使用全局时空有限元模型来改进 计算的可重复性，同时保持高精度， 与本地计算方法相比。 方法和结果：我们 考虑大心肌区域的分区， 时变基本网格单元。 的节点 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了 每个网格单元的时变域。 在每个元素中，我们 使用有限元形状函数对运动学建模。 在 在一个实施方式中，参考状态网格配置由 用户和后续网格配置的初始估计 通过对节点的独立跟踪获得，我们迭代地细化 网格配置通过将速度数据拟合到 时空有限元模型 计算机的再现性 可以在每次计算之后分析量。 中 验证研究，我们合成了一个二维非均匀变形数据集 其表观SNR为45。 我们计算了它的运动和变形 分析案例1中的单个三角形网格单元得到的量 并分析了一个扩展的网格配置， 同一元素加上三个相邻的元素 案例2中的尺寸。 重复数据合成和分析1000次 平均值和标准差的测量结果表明， 的估计数量与真实情况非常吻合。 这两种情况下的价值观。 比较相同网格单元的结果 在这两种情况下，表明扩展网格建模导致 标准差较低，但准确度较高。 总结和 结论：用本文方法分析单元素域 和先前的局部方法具有大致相同的再现性。 采用本文方法，通过增加 更多的三角形元件实现了增加的再现性。 在 同时，由于分段参数化， 精度，可比的地方方法，仍然可以 得到了

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.