左心室壁局部范围MRI三维有限元应变解析

  • 摘要: 利用磁共振标记技术对左心室壁进行局部三维有限元应变的分析. 在一个心动周期内,分别拍摄24张短轴平面图像和长轴平面图像,然后进行合成,求解出健康人左心室壁上各个位置不同时刻的位移和应变,为临床应用和定量准确地评价心功能提供重要的理论依据.

     

    Abstract: This paper proposes a three-dimensional analysis method in local regionsof the left ventricle by using tagged MR imaging. The imaging slices aretaken in long axis and short axis of LV wall. At least two parallel slicesare prepared in each axis. The material points of interest are tracedbetween different phases of beating heart. Two points are chosen on eachintersection line of image slices which surround the trace point.Three-dimensional displacements of a point on an intersection line are derivedfrom the two-dimensional displacements on the two perpendicular slices. By use ofthe interpolation function of a hexahedral element in FEM, the displacement anddeformation gradients are derived from the displacements of eight nodes.Displacements of points at systole with respect to diastole can be calculatedas a sum of each displacement between each phase of beating. Green's strainis also obtained by using a product of deformation gradient between eachphase. The proposed method has an advantage of reducing the time ofcalculation by not tracing all nodal points of the finite elements inthe LV wall.

     

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