Four-chamber surface model from segmented cardiac MRI

Abstract

This paper presents a novel method for the generation of a four-chamber surface model from segmented cardiac MRI. The method has been tested on 3D short-axis cardiac magnetic resonance images with strongly anisotropic voxels in the long-axis direction. It provides a smooth triangulated surface mesh that closely follows the endocardium and epicardium. The surface triangles are close-to-regular and their number can be preset. The input to the method is the segmentation of each of the four cardiac chambers. The same algorithm is independently used to generate the surface mesh of the epicardium and of the endocardia of the four cardiac chambers. For each chamber, a sphere that includes the chamber is centered at its barycenter. A triangulated surface mesh with almost perfectly regular triangles is constructed on the sphere. Then, the Laplace equation is solved over the region bounded by the segmented chamber surface and the sphere. Finally, each vertex from the triangulated mesh on the sphere is mapped from the sphere to the chamber surface by following the gradient flow of the solution of the Laplace equation. The proposed method was compared to the marching cubes algorithm. The proposed method provides a smooth mesh of the heart chambers despite the strong voxel anisotropy of the 3D images. This is not the case for the marching cubes algorithm, unless the mesh is significantly smoothed. However, the smoothing of the mesh shrinks it, which makes it a less accurate representation of the chamber surface. The second advantage is that the mesh triangles are more regular for the proposed method than for the marching cubes algorithm. Finally, the proposed method allows for a finer control of the number of triangles than the marching cubes algorithm.