Prassl Anton J, Kickinger Ferdinand, Ahammer Helmut, Grau Vicente, Schneider Jürgen E, Hofer Ernst, Vigmond Edward J, Trayanova Natalia A, Plank Gernot
Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21218 USA.
IEEE Trans Biomed Eng. 2009 May;56(5):1318-30. doi: 10.1109/TBME.2009.2014243. Epub 2009 Feb 6.
Significant advancements in imaging technology and the dramatic increase in computer power over the last few years broke the ground for the construction of anatomically realistic models of the heart at an unprecedented level of detail. To effectively make use of high-resolution imaging datasets for modeling purposes, the imaged objects have to be discretized. This procedure is trivial for structured grids. However, to develop generally applicable heart models, unstructured grids are much preferable. In this study, a novel image-based unstructured mesh generation technique is proposed. It uses the dual mesh of an octree applied directly to segmented 3-D image stacks. The method produces conformal, boundary-fitted, and hexahedra-dominant meshes. The algorithm operates fully automatically with no requirements for interactivity and generates accurate volume-preserving representations of arbitrarily complex geometries with smooth surfaces. The method is very well suited for cardiac electrophysiological simulations. In the myocardium, the algorithm minimizes variations in element size, whereas in the surrounding medium, the element size is grown larger with the distance to the myocardial surfaces to reduce the computational burden. The numerical feasibility of the approach is demonstrated by discretizing and solving the monodomain and bidomain equations on the generated grids for two preparations of high experimental relevance, a left ventricular wedge preparation, and a papillary muscle.
在过去几年中，成像技术取得了重大进展，计算机性能也大幅提升，这为构建具有前所未有的详细程度的心脏解剖逼真模型奠定了基础。为了有效地将高分辨率成像数据集用于建模目的，必须对成像对象进行离散化处理。对于结构化网格来说，这个过程很简单。然而，为了开发通用的心脏模型，非结构化网格更为可取。在本研究中，提出了一种基于图像的新型非结构化网格生成技术。它使用直接应用于分割后的三维图像堆栈的八叉树对偶网格。该方法生成共形、边界拟合且以六面体为主的网格。该算法完全自动运行，无需交互操作，并且能够生成具有光滑表面的任意复杂几何形状的精确保体积表示。该方法非常适合心脏电生理模拟。在心肌中，该算法使单元尺寸的变化最小化，而在周围介质中，单元尺寸随着与心肌表面距离的增加而增大，以减轻计算负担。通过在生成的网格上离散化并求解单域和双域方程，对两种具有高度实验相关性的标本（左心室楔形标本和乳头肌）进行模拟，证明了该方法在数值上的可行性。
