title: Combined SPHARM-PDM and entropy-based particle systems shape analysis framework.
abstract: The NA-MIC SPHARM-PDM Toolbox represents an automated set of tools for the computation of 3D structural statistical shape analysis. SPHARM-PDM solves the correspondence problem by defining a first order ellipsoid aligned, uniform spherical parameterization for each object with correspondence established at equivalently parameterized points. However, SPHARM correspondence has shown to be inadequate for some biological shapes that are not well described by a uniform spherical parameterization. Entropy-based particle systems compute correspondence by representing surfaces as discrete point sets that does not rely on any inherent parameterization. However, they are sensitive to initialization and have little ability to recover from initial errors. By combining both methodologies we compute reliable correspondences in topologically challenging biological shapes.
  
  
  METHODS
  Diverse subcortical structures cohorts were used, obtained from MR brain images.
  
  
  METHODS
  The SPHARM-PDM shape analysis toolbox was used to compute point based correspondent models that were then used as initializing particles for the entropy-based particle systems. The combined framework was implemented as a stand-alone Slicer3 module, which works as an end-to-end shape analysis module.
  
  
  RESULTS
  The combined SPHARM-PDM-Particle framework has demonstrated to improve correspondence in the example dataset over the conventional SPHARM-PDM toolbox.
  
  
  CONCLUSIONS
  The work presented in this paper demonstrates a two-sided improvement for the scientific community, being able to 1) find good correspondences among spherically topological shapes, that can be used in many morphometry studies 2) offer an end-to-end solution that will facilitate the access to shape analysis framework to users without computer expertise.
authors.affiliation: University of North Carolina at Chapel Hill, Department of Psychiatry;
authors.forename: Beatriz
authors.initials: B
authors.lastname: Paniagua
authors.forename: Lucile
authors.initials: L
authors.lastname: Bompard
authors.forename: Josh
authors.initials: J
authors.lastname: Cates
authors.forename: Ross
authors.initials: R
authors.lastname: Whitaker
authors.forename: Manasi
authors.initials: M
authors.lastname: Datar
authors.forename: Clement
authors.initials: C
authors.lastname: Vachet
authors.forename: Martin
authors.initials: M
authors.lastname: Styner
keywords: 3DSlicer; Spherical harmonic representation; entropy-based particle systems; shape analysis framework; statistical shape analysis
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