title: Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.
abstract: OBJECTIVE
  The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms.
  
  
  METHODS
  Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation.
  
  
  RESULTS
  We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful.
  
  
  CONCLUSIONS
  The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.
authors.affiliation: Department of Radiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8655, Japan. mwatanab-tky@umin.ac.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Watanabe
authors.forename: Shigeki
authors.initials: S
authors.lastname: Aoki
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Masutani
authors.forename: Osamu
authors.initials: O
authors.lastname: Abe
authors.forename: Naoto
authors.initials: N
authors.lastname: Hayashi
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Masumoto
authors.forename: Harushi
authors.initials: H
authors.lastname: Mori
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kabasawa
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
mesh_terms: D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology; D002482:Cellulose; D032561:Cotton Fiber; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging; D006801:Humans; D009757:Nylons; D019047:Phantoms, Imaging; D018583:Pliability; D011091:Polyesters
chemical_list: D009757:Nylons; D011091:Polyesters; D002482:Cellulose; C012024:rayon, purified