Ultrasonic ray-tracing based endocardial surface reconstruction

Accurate and fast reconstruction of the endocardium is a fundamental step for performing a successful ablation operation. This paper proposes an ultrasonic ray-tracing based endocardial surface reconstruction algorithm, which utilizes a new proposed non-contact ultrasonic catheter. The proposed catheter is composed of an electromagnetic position sensor and three miniature transducers, and it can sample a point cloud from the targeted endocardium in real-time. The 3D Delaunay triangulation of the sampled point cloud is first calculated, and then each tetrahedron is marked internal or external via ultrasonic ray-tracing and the boundary of all internal tetrahedra is extracted as a coarse surface mesh. Finally, HC Laplacian is applied to smooth the coarse mesh for the benefit of avoiding shrinkages. The basic idea of the proposed surface reconstruction algorithm relies on the fact that tetrahedra intersecting with the ultrasonic rays provide a volumetric estimation of the measured heart. Simulations on a heart phantom are given to support the superiority of the proposed algorithm. Compared to the prior arts, the proposed algorithm could reconstruct a realistic endocardial surface while preserving the features of vena cava and atrium appendage without shrinkages.