Muscle Modeler  
  Objective quantification of architectural parameters (e.g., fascicle length, pennation angle, physiological cross-sectional area and volume) and 3D reconstruction of surface and volume geometry  
  Methods dissection and digitization of cadaveric specimens (MicroScribe G2X) and ultrasonography  
  Outputs architectural analysis and geometric mesh (triangular and tetrahedral)  
  Applications cadaveric studies : extensor/flexor forearm muscles, supraspinatus/infraspinatus, pectoralis major, vastusmedialis, piriformis, sacral nerves, ACL/PCL ligaments, humerus tendon rupture. in-vivo studies: supraspinatus/infraspinatus (current)  
  Development C/C++, MFC, OpenGL, BLAS, LAPACK, TAUCS, MS Windows platforms  
  Keywords dissection, digitization, cubic spline, voronoi-tessellation, level-set method, tetrahedralization, Laplacian surface, linear/non-linear least squares, finite element method  


  Screenshot examples  
  Mainframe and examples of dialog-based control (editing digitized points, anatomical frame estimation and fascicular investigation)  
  Main features include basic geometric manipulation, architectural analysis, surface/volume extraction, FEM-based muscle deformation, geometric deformation, virtual ultrasound imaging, digitization error reduction, geometric cross-matching of architectures, 3D registration and etc.  
  Reconstruction of surface and volume geometry   
  Digitized fascicles are wrapped around by the closed surface that is tracked using the level-set method. Associated implicit functions are determined based on the estimated anatomical cross-sectional area of each fascicle (i.e., elliptical and piecewise cylinders). Those functions are carefully blended by using the locally-weighted interpolation, which controls smoothness and prevents undesired geometric defects (e.g., hole, gaps, concavity). Brachioradialis is shown in figures.  
  Estimation of line of action  
  Linear regression is used to determine line of action (intra-and extra muscular tendon direction) of pennate muscles. (a. supraspinatus and b. vastusmedialis)  
  Assessment of intramuscular variation of pennation angle  
  It is observed that muscles may have strong pattern of pennation angle distribution with respect to anatomical axis. Proximodistal, lateromedial and superficial to deep axes are accounted for presented studies.  


  Estimation of physiological cross-sectional area  
  Voronoi-tessellation is used to approximate cross-sectional area of each fascicle. This method iteratively computes all fascicles and their points. Our study uses 30-60K re-sampled points, depending on architectural complexity or size.   
  Integration of ultrasonographic assessment for in-vivo architectural modeling   
  Our study stresses that anatomical details are needed to enhance reliability and reproducibility of ultrasonography. Furthermore, it is demonstrated how effectively ultrasonographic non-invasive assessment can be complemented by cadaveric invasive measurement (paper under review). This is currently being implemented into practical application. Details will be given soon.   
  Ultrasonographic assessment vs virtual (simulated) ultrasound  
  3D Registration for muscle architecture (fitting cadaveric model to in-vivo ultrasonographic assessment)