结合有限元和非刚体运动估计的左心室应变分析

Strain Analysis of Left Ventricle by Integrating Finite Element Model and Non-rigid Motion Estimation

提出一种直观地分析左心室在心脏收缩期的应变情况的方法.首先利用心脏核磁共振图像数据对左心室进行三维实体建模,再进行有限元单元划分;然后,使用非刚体运动估计算法——单位法线及高斯曲率混合算法,在左心室收缩期相邻时刻的有限元模型表面上寻找最相似单元结点作为对应单元结点,计算各对应结点间的位移,并用α剪枝平均对位移过大的可疑结点进行处理;最后,利用弹塑性力学中应变与位移间的几何关系求解左心室表面各单元结点的应变,获得位移和应变的彩色云图.实验结果表明,该方法能直观、有效地反映左心室表面在整个心脏收缩期的形变情况和应变分布.

A strain analysis approach of the left ventricle （LV） is proposed. In this approach, we can intuitively analyze the strain of the LV during systole. First, we build a 3D solid model by utilizing the cardiac magnetic resonance （MR） images, and then construct a 3D finite element model. Second, we calculate the correspondence points of element nodes on the finite element model surface by utilizing hybrid unit normal/Gaussian curvature （UNGCK） algorithm. UNGCK algorithm is a non-rigid motion estimation technique. Lastly, we use α-trimmed means to correct the displacement of the suspicious node. We estimate the strain of the LV by using the knowledge of elasticity and plasticity, and then acquire color cloud pictures of the deformation and strain distribution. Our experiments indicate that the strain analysis approach of the LV can intuitively and effectively reflect the strain distribution and deformation trends of surfaces of the LV during systole.