Left Ventricle Motion Analysis
Tagged MRI(TMRI) provides a direct and noninvasive way to reveal the in-wall deformation of the myocardium. The 3D trajectories and strain of material points cannot be calculated directly from 2D TMRI images due to the through-plane motion. The intersections of three orthogonal tagging lines are material points in the myocardium. A generic heart mesh is registered on the TMRI with polar decomposition. We propose a novel meshless deformable model for in-vivo cardiac motion estimation from tagged MRI. Meshless deformable models describe an object as point clouds inside of the object boundary. The similarity transformation of each point is computed by assuming its neighboring points are doing the same transformation. The deformation is computed iteratively when the cue points matches the target points in the consecutive image frame. The 3D strain field is computed from the 3D displacement field with Moving Least Squares (MLS). We demonstrate that meshless deformable models outperform the finite element method (FEM) with a numerical phantom. Meshless deformable models can track the trajectories of any material point in myocardium and compute the 3D strain field of the myocardium. The experimental results on in-vivo healthy and patient heart data show that the meshless deformable model can fully recover the myocardium motion in 3D.