A Procedural Method for Modeling the Purkinje Fibers of the Heart
A Procedural Method for Modeling the Purkinje Fibers of the Heart
复制标题
DOI：
10.2170/physiolsci.rp003208
复制
发表时间：
2008-12-01
影响因子：
2.3
通讯作者：
Nakazawa, Kazuo
中科院分区：
文献类型：
--
作者：
Ijiri, Takashi;Ashihara, Takashi;Nakazawa, Kazuo
浦肯野纤维位于心脏的心室壁中，就在内膜下方，并将兴奋从右束支和左束支传导到心室心肌。最近，解剖学家成功地拍摄了一只绵羊的浦肯野纤维，清晰地显示了浦肯野纤维的网状结构。在这项研究中，我们提出了一种技术，半自动使用扩展的L-系统的浦肯野纤维的网格结构建模。L系统是一种形式文法，它通过生成规则（或重写规则）和初始结构来定义分形结构的增长。它最初被制定为描述植物细胞的生长，随后被应用于计算机图形学的各种目的，如建模植物，建筑物，街道和装饰品。为了达到我们的目的，我们对L-系统的生长过程进行了如下扩展：1）每个生长的分支尽可能远离已有的分支以形成均匀分布; 2）当分支碰撞时，我们将碰撞的分支连接起来以构造一个封闭的网格结构.我们设计了一个生成规则的基础上观察浦肯野纤维的照片和手动指定的三个终端位置的三维（3D）心脏模型：右束分支，前束，左后束的左分支。然后，我们根据指定的生成规则从三个位置中的每一个开始生长纤维。我们实现了生成浦肯野纤维的3D模型，其物理外观与真实的照片非常相似。生成需要几秒钟。通过修改生成规则和参数，可以很容易地构造出浦肯野纤维的变体。
The Purkinje fibers are located in the ventricular walls of the heart, just beneath the endocardium and conduct excitation from the right and left bundle branches to the ventricular myocardium. Recently, anatomists succeeded in photographing the Purkinje fibers of a sheep, which clearly showed the mesh structure of the Purkinje fibers. In this study, we present a technique for modeling the mesh structure of Purkinje fibers semiautomatically using an extended L-system. The L-system is a formal grammar that defines the growth of a fractal structure by generating rules (or rewriting rules) and an initial structure. It was originally formulated to describe the growth of plant cells, and has subsequently been applied for various purposes in computer graphics such as modeling plants, buildings, streets, and ornaments. For our purpose, we extended the growth process of the L-system as follows: 1) each growing branch keeps away from existing branches as much as possible to create a uniform distribution, and 2) when branches collide, we connect the colliding branches to construct a closed mesh structure. We designed a generating rule based on observations of the photograph of Purkinje fibers and manually specified three terminal positions on a three-dimensional (3D) heart model: those of the right bundle branch, the anterior fascicle, and the left posterior fascicle of the left branch. Then, we grew fibers starting from each of the three positions based on the specified generating rule. We achieved to generate 3D models of Purkinje fibers of which physical appearances closely resembled the real photograph. The generation takes a few seconds. Variations of the Purkinje fibers could be constructed easily by modifying the generating rules and parameters.