Mesin Luca, Farina Dario
Laboratorio di Ingegneria del Sistema Neuromusculare LISiN, Dipartimento di Elettronica, Politecnico di Torino, 10129 Torino, Italy.
IEEE Trans Biomed Eng. 2005 Dec;52(12):1984-93. doi: 10.1109/TBME.2005.857670.
Most models for surface electromyography (EMG) signal generation are based on the assumption of space-invariance of the system in the direction of source propagation. This assumption implies the same shape of the potential distribution generated by a source in any location along the propagation direction. In practice, the surface EMG generation system is not space invariant and, therefore, the surface signal detected along the direction of the muscle fibers may significantly change shape along the propagation path. An important class of nonspace invariant systems is that of volume conductors inhomogeneous in the direction of source propagation. In this paper, we focused on inhomogeneities introduced by the presence of spheres of different conductivities with respect to the tissue where they are located. This effect may prove helpful to model the presence of glands, vessels, or local changes in the conductivity of a tissue. We present an approximate analytical solution that accounts for an arbitrary number of spheres in an arbitrary complex volume conductor. As a representative example, we propose the solution for a planar layered volume conductor, comprised of fat and muscle layers with spherical inhomogeneities inside the fat layer. The limitations of the approximations introduced are discussed. The model is computationally fast and constitutes an advanced means for the analysis and interpretation of surface EMG signal features.
大多数表面肌电图（EMG）信号生成模型是基于系统在源传播方向上空间不变性的假设。这一假设意味着源在沿传播方向的任何位置所产生的电位分布形状相同。实际上，表面EMG生成系统并非空间不变的，因此，沿肌纤维方向检测到的表面信号在传播路径上的形状可能会显著变化。一类重要的非空间不变系统是在源传播方向上不均匀的体积导体。在本文中，我们关注的是由相对于其所在组织具有不同电导率的球体的存在所引入的不均匀性。这种效应可能有助于对腺体、血管的存在或组织电导率的局部变化进行建模。我们提出了一种近似解析解，该解考虑了任意复杂体积导体中任意数量的球体。作为一个代表性示例，我们给出了一个平面分层体积导体的解，该导体由脂肪层和肌肉层组成，脂肪层内有球形不均匀性。讨论了所引入近似的局限性。该模型计算速度快，是分析和解释表面EMG信号特征的一种先进方法。
