title: Averaging of diffusion tensor imaging direction-encoded color maps for localizing substantia nigra.
abstract: Diffusion tensor imaging (DTI) is a form of MRI that has been used extensively to map in vivo the white matter architecture of the human brain. It is also used for mapping subcortical nuclei because of its general sensitivity to tissue orientation differences and effects of iron accumulation on the diffusion signal. While DTI provides excellent spatial resolution in individual subjects, a challenge is visualizing consistent patterns of diffusion orientation across subjects. Here we present a simple method for averaging direction-encoded color anisotropy maps in standard space, explore this technique for visualizing the substantia nigra (SN) in relation to other midbrain structures, and show with signal-to-noise analysis that averaging improves the direction-encoded color signature. SN is distinguished on averaged maps from neighboring structures, including red nucleus (RN) and cerebral crus, and is proximal to SN location from existing brain atlases and volume of interest (VOI) delineation on individual scans using two blinded raters.
authors.affiliation: Department of Psychology, The City College of the City University of New York, New York, NY, USA; Program in Behavioral and Cognitive Neuroscience, The City College of the City University of New York, New York, NY, USA. Electronic address: tellmore@ccny.cuny.edu.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Ellmore
authors.affiliation: Department of Psychology, The City College of the City University of New York, New York, NY, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Murphy
authors.affiliation: Department of Psychology, The City College of the City University of New York, New York, NY, USA.
authors.forename: Katarina
authors.initials: K
authors.lastname: Cruz
authors.affiliation: Department of Internal Medicine, The University of Texas Medical School at Houston, Houston, TX, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Castriotta
authors.affiliation: Department of Neurology and UT MOVE, The University of Texas Medical School at Houston, Houston, TX, USA.
authors.forename: Mya C
authors.initials: MC
authors.lastname: Schiess
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D013378:Substantia Nigra / Q000502:physiology*
keywords: Basal ganglia; Diffusion tensor imaging; Midbrain; Red nucleus; Substantia nigra