title: Parametrization of white matter manifold-like structures using principal surfaces.
abstract: In this manuscript, we are concerned with data generated from a diffusion tensor imaging (DTI) experiment. The goal is to parameterize manifold-like white matter tracts, such as the corpus callosum, using principal surfaces. The problem is approached by finding a geometrically motivated surface-based representation of the corpus callosum and visualized fractional anisotropy (FA) values projected onto the surface. The method also applies to any other diffusion summary. An algorithm is proposed that 1) constructs the principal surface of a corpus callosum; 2) flattens the surface into a parametric 2D map; 3) projects associated FA values on the map. The algorithm is applied to a longitudinal study containing 466 diffusion tensor images of 176 multiple sclerosis (MS) patients observed at multiple visits. For each subject and visit the study contains a registered DTI scan of the corpus callosum at roughly 20,000 voxels. Extensive simulation studies demonstrate fast convergence and robust performance of the algorithm under a variety of challenging scenarios.
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, MD, 21205.
authors.forename: Chen
authors.initials: C
authors.lastname: Yue
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, MD, 21205.
authors.forename: Vadim
authors.initials: V
authors.lastname: Zipunnikov
authors.affiliation: Department of Neurophysics, Max Planck Institute, Leipzig, Germany, 04103.
authors.forename: Pierre-Louis
authors.initials: PL
authors.lastname: Bazin
authors.affiliation: Center for Neuroscience and Regenerative Medicine, Henry Jackson Foundation, Bethesda, MD 20892.
authors.forename: Dzung
authors.initials: D
authors.lastname: Pham
authors.affiliation: Department of Radiology and Imaging Sciences, National Institute of Health, Bethesda, MD 20892.
authors.forename: Daniel
authors.initials: D
authors.lastname: Reich
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, MD, 21205.
authors.forename: Ciprian
authors.initials: C
authors.lastname: Crainiceanu
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, MD, 21205.
authors.forename: Brian
authors.initials: B
authors.lastname: Caffo
keywords: Corpus Callosum; Principal Curves and Surfaces; Thin Plate Splines